Leather and Footwear Sustainability: Manufacturing, Supply Chain, and Product Level Issues [1st ed.] 9789811562952, 9789811562969

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Textile Science and Clothing Technology

Subramanian Senthilkannan Muthu   Editor

Leather and Footwear Sustainability Manufacturing, Supply Chain, and Product Level Issues

Textile Science and Clothing Technology Series Editor Subramanian Senthilkannan Muthu, SgT Group & API, Hong Kong, Kowloon, Hong Kong

This series aims to broadly cover all the aspects related to textiles science and technology and clothing science and technology. Below are the areas fall under the aims and scope of this series, but not limited to: Production and properties of various natural and synthetic fibres; Production and properties of different yarns, fabrics and apparels; Manufacturing aspects of textiles and clothing; Modelling and Simulation aspects related to textiles and clothing; Production and properties of Nonwovens; Evaluation/testing of various properties of textiles and clothing products; Supply chain management of textiles and clothing; Aspects related to Clothing Science such as comfort; Functional aspects and evaluation of textiles; Textile biomaterials and bioengineering; Nano, micro, smart, sport and intelligent textiles; Various aspects of industrial and technical applications of textiles and clothing; Apparel manufacturing and engineering; New developments and applications pertaining to textiles and clothing materials and their manufacturing methods; Textile design aspects; Sustainable fashion and textiles; Green Textiles and Eco-Fashion; Sustainability aspects of textiles and clothing; Environmental assessments of textiles and clothing supply chain; Green Composites; Sustainable Luxury and Sustainable Consumption; Waste Management in Textiles; Sustainability Standards and Green labels; Social and Economic Sustainability of Textiles and Clothing.

More information about this series at http://www.springer.com/series/13111

Subramanian Senthilkannan Muthu Editor

Leather and Footwear Sustainability Manufacturing, Supply Chain, and Product Level Issues

123

Editor Subramanian Senthilkannan Muthu SgT Group & API Hong Kong, Kowloon, Hong Kong

ISSN 2197-9863 ISSN 2197-9871 (electronic) Textile Science and Clothing Technology ISBN 978-981-15-6295-2 ISBN 978-981-15-6296-9 (eBook) https://doi.org/10.1007/978-981-15-6296-9 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

This book is dedicated to: The lotus feet of my beloved Lord Pazhaniandavar; My beloved late father; My beloved mom; My beloved wife Karpagam; My beloved Daughters Anu and Karthika; My beloved brother Raghavan; Last but not least To everyone working in Leather and Footwear Sector to make it Sustainable.

Contents

Environmental and Chemical Issues in Tanneries and Their Mitigation Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. Senthil Kumar and G. Janet Joshiba

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Leather in the Age of Sustainability: A Norm or Merely a Cherry on Top? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mukta Ramchandani and Ivan Coste-Maniere

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Blockchain Technology in Footwear Supply Chain . . . . . . . . . . . . . . . . Hao Cui and Karen K. Leonas

23

Designer Activism Strategies for Sustainable Leather Product Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Nithyaprakash, S. Niveathitha, and V. Shanmugapriya

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Bacterial Cellulose—A Sustainable Alternative Material for Footwear and Leather Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. Rathinamoorthy and T. Kiruba

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The Chromium Recovery and Reuse from Tanneries: A Case Study According to the Principles of Circular Economy . . . . . . . . . . . . . . . . . 123 Evgenios Kokkinos and Anastasios I. Zouboulis Conviviality in Leather and Fashion Entrepreneurial Communities: Emerging Results from an Exploratory Research . . . . . . . . . . . . . . . . . 159 Simone Guercini and Silvia Ranfagni Certifications for Sustainability in Footwear and Leather Sectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 P. Senthil Kumar and C. Femina Carolin

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viii

Contents

Brazilian Sustainability Outlook in Footwear Sector . . . . . . . . . . . . . . . 199 Lais Kohan, Cristiane Reis Martins, Heloisa Nazare dos Santos, Palloma Renny Beserra Fernandes, Fernando Brandao, and Julia Baruque-Ramos Waste and 3R’s in Footwear and Leather Sectors . . . . . . . . . . . . . . . . . 261 Nilesh C. Jadhav and Akshay C. Jadhav

About the Editor

Dr. Subramanian Senthilkannan Muthu is currently Head of Sustainability at the SgT Group and API in Hong Kong. He holds a Ph.D. from The Hong Kong Polytechnic University. He is a leading expert in the areas of environmental sustainability in textiles and the clothing supply chain, product life cycle assessment (LCA) and product carbon footprint (PCF) assessment in various industrial sectors and has extensive industrial experience in these fields. He has published more than 75 research papers, written numerous chapters and authored/edited over 80 books.

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Environmental and Chemical Issues in Tanneries and Their Mitigation Measures P. Senthil Kumar and G. Janet Joshiba

Abstract In spite of the fact that the tanning industry is known to be one of the main financial parts in numerous nations, there has been an expanding ecological concern with respect to the arrival of different hard-headed contaminations in tannery wastewater. The releasing and dumping of squanders close to the water bodies without treatment make it nearly look like a territory which is lying under the cover of contamination. It is a developing issue for all the living organisms and the wellness of the environment. This chapter elaborates the various environmental and chemical issues’ cause due to the tanneries and their impact towards the environment. In addition, it also clearly explains the mitigation measures followed in the tannery industry to reduce its pollution level. Keywords Tannery · Contaminations · Wellness · Mitigation · Environment

1 Introduction In current scenario, the generation of wastes from various domains such as agriculture, transport, mining, industry and energy sectors is of prime environmental concern, and also it is considered to be one of the greatest threats to the wellness of the environment. Once more, among all the modern squanders tannery effluents are positioned as the most elevated toxins. On account of the generally modest expense of work and materials, over a large portion of the world’s tanning business happens in predominantly in the developing nations. It has been reported that during the period of 1970–1995, the production of light leather materials progressively increased from 35 to 56% and the production of heavy leather materials progressively increased from 26 to 56% [2]. The leather industries are one of the important industries which play a vital role in the lifestyle of human beings. Basically, the raw animal skins are processed by converting the animal skin and hides into leather which can be used further for P. Senthil Kumar (B) · G. Janet Joshiba Department of Chemical Engineering, SSN College of Engineering, Chennai 603110, India e-mail: [email protected]; [email protected]; [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. S. Muthu (ed.), Leather and Footwear Sustainability, Textile Science and Clothing Technology, https://doi.org/10.1007/978-981-15-6296-9_1

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manufacturing various essential things for humans. The waste skin materials from the slaughter house are used as the key material in the tannery industries; further, the tanneries lessen the burden of disposal of slaughter house by utilizing the skin waste which is not suitable for the edible usage. Several reports have claimed that the tannery is one of the highest pollution-creating industries because of the strong and toxic chemicals used in the processing of the animal skins. The implementation of sustainable and cleaner wastewater treatment technologies in the tanneries helps in lessening the negative impacts of the tannery wastewaters towards environment. In addition, with consistently expanding interest for new water and the water assets getting rare, the decrease of soil fruitfulness because of the defilement by the saline wastewater from the enterprises are significant issue in Indian states, for example, Tamil Nadu [1]. As per the investigation of Blacksmith Institute, it is reported that around 75% of the chromium-polluted sites are present in South Asia and their nearby countries. In addition, the major source of chromium pollution occurs from the industrial sources such as tannery, metallurgy and mining industries. Among these industries, the tanneries present in South Asian countries contribute greatly to a higher amount of generation of chromium into the environment [2]. The tannery wastewater is considered to be one of the highly toxic pollutants because of its toxic composition and its deleterious effects. The colour, higher oxygen demand, toxic metals, dyes and other poisonous chemicals make the tannery effluent more complex to degrade, and also it is highly difficult to treat using the wastewater treatment technologies. In different stages of preparation of leather such as soaking, tanning and post-tanning, various chemicals such as wetting agents, ammonium sulphide, sodium sulphite, ammonium chloride, soda ash, CaO and enzymes are involved in the tannery industry. The disposal of the above-mentioned tannery waste into surface and groundwaters without proper treatment results in negative impacts towards the environment causing health disorders and environmental effects [3]. This chapter clearly explains the various environmental and chemical effects of the tanneries, and also it includes the various mitigation measures to combat the negative impacts of the leather industry. It also focuses on the various treatment technologies used to eliminate the toxic compounds from the tannery wastewater.

2 Overview of Tannery Wastewater The tannery wastewater is composed of various compounds such as pH, BOD, nitrogen, sulphides, suspended solids, settleable solids, gross solids, fats, oils and grease, heavy metals, dyes and toxic chemicals [4]. The significance of ecological gauges in India’s fare was first experienced when Germany, one of the significant merchants of cowhide and calfskin merchandise from India, restricted the import of cowhide items containing in excess of 5 mg/kg of pentachlorophenol (PCP) in 1990. This was trailed by a German prohibition on the import of cowhide and materials treated with various Azo colours in 1994. In India, the significant bunches of tanning businesses are Ambur, Pallavaram, Vaniyambadi, Pernambut, Dindigul,

Environmental and Chemical Issues in Tanneries …

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Table 1 Characteristics of tannery wastewater No.

Characteristics

Average concentration in mg/l (before treatment)

Average concentration in mg/litre (after treatment)

1.

BOD

1850

700

2.

COD

4500

3000

3.

Suspended solids

3750

1500

4.

Chloride

5500

1200

5.

Chromium

165

38

Source [7]

Ranipet and Trichy in Tamil Nadu; Kolkata in West Bengal; Kanpur in Uttar Pradesh; and Jalandhar in Punjab. Around 45% of the all the tanneries in India are situated at Tamil Nadu. In Tamil Nadu, the significant tannery bunches are situated at Vellore district [1]. The characteristics of the tannery wastewater are clearly explained in Table 1. The generation of effluent containing chromium is one of the major threats to the environmental issues. Chromium is a profoundly lethal compound, and the dumping of chromium containing material is in many nations limited to a couple of uncommon dumping grounds. Outflows into the air are essentially identified with vitality use, yet additionally the utilization of natural solvents and colour causes discharges into the air. The production of fresh animal hides has been calculated at about 8–9 million ton per year. Nearly 1.4 million tonnes of soil waste are generated during the production of hides. For each ton of crude conceal prepared, the measures of strong waste and results might be delivered. Assortment and safe removal of strong waste, particularly chrome containing strong waste and slime, are ordinarily checked by natural specialists and related with costs. In any occasion, decrease of waste is basic so as to satisfy needs for diminished contamination load from tanneries [5]. Around 15% of solid waste flushing out of the tanneries is a mixture of both solid and liquid materials in which 29% in the liquid state. Several chemicals such as formic acid, chromium oxide, sodium chloride, ammonium sulphate and sulphuric acid are utilized in the processing of leather. In addition, the HCl, caustic soda, formic acid, chromium, sodium arsenite, soda ash, sulphuric acid and arsenic sulphate are utilized in the various tanning process such as soaking, liming, deliming and tanning processes. After every consequent operation, water is used to wash and clean the chemicals and machineries. A huge part of solid waste is generated from the trimmings, shavings, buffing, curing and packaging of the animal skins or hides. In 2015, Kavitha and Ganapathy have investigated about the environmental impact of tannery process in the Vellore district, Tamil Nadu. The studies showed that the water utilization for the creation of skin from one tone of crude covers up is around 15,000–40,000 l and 110–260 l for every sheep skin. Quality synthetic substances and ideal dosing in each procedure can lead to downing the contamination level, and along these lines diminish the ecological effect. Cutting-edge innovations are

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followed in the tanneries based on reusing and recuperating procedures that lead to the improvement of calfskin quality. The wastewater from the tanneries been treated in the emanating treatment plants utilizing reverse assimilation (RO) innovation and changed over into reusable water for the tannery forms and the reject from the RO treatment being vanished either by nearby planetary group or by mechanical dissipation and changed over into salt. In this manner, the ecological effect of tannery industry in Tamil Nadu, India, has radically diminished by accomplishing Zero Liquid Release framework [1]. Tinni et al. have investigated the impingement of tannery effluent on the environment of Dhaka city corporation. They concluded that the solid and liquid of around 56% waste flushing out of the tanneries are in black colour and causes noxious smell in the environment. In addition, the disposal of tannery effluents without proper treatment causes health disorders such as skin disease, diarrhoea, dizziness, asthma, fever and respiratory issues. It also affects the aquatic life and other living organisms by creating various negative effects on the environment [6]. Rahaman et al. have conducted a comparative study of the various concentrations of heavy metals in different layers of vicinity soil and agricultural soil. The studies showed that heavy metals’ concentration was found to be higher in the aquatic region than the normal agricultural land. This metal focus in soil is mindful for the advancement of lethality in horticultural items. In this way, the human well-being and condition are influenced by these territories [8].

3 Process Involved in Tanneries Tanning is the process of conversion of protein present in the raw animal skin into a strong material which can be used for wide variety of applications. The tanned leather changes into a flexible form, and it does not get rancid when it is wetted back with water. The leather tanning process involves various stages of processing of raw skin. Initially, the animal skin is prepared using some preparatory stages such as: • Preservation—The animal skin is subjected to a preservation treatment to protect it from decomposition • Soaking—Water is used in this method to wash or hydrate the skin • Liming—Elimination of undesirable protein and opening up is achieved • Unhairing—Elimination of animal hair from the skin • Fleshing—Removal of subcutaneous material • Splitting—The animal skin is cut into two or mo • Rehorizontal layers • Reliming—Further elimination of protein and opening-up process • Deliming—Removal of liming and unhairing chemicals from the skin • Bating—Further proteins are removed using the proteolytic proteins and undergoes softening process • Degreasing—Removal of natural fats, oils and grease from the skin/hide

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• Frizing—Physical removal of fat layer inside the skin • Bleaching—Chemical modification of darker pigmented skins into light coloured pelt • Pickling—Lowering of pH value to acidic region • Depickling—Increasing of pH to acidic region. After the preparatory stages, the prepared skin is subjected into various stages such as tanning, dyeing and finishing procedures. The tanning process is of two types such as vegetable tanning and chrome tanning [4]. In the pretanning process, the prepared skin is subjected into pretanning operations which include soaking, fleshing, trimming, bating and pickling processes. In the chrome tanning process, the chromium is fixed by slowly increasing the pH by addition of base. The crosslinkage of chromium ions with carboxyl groups results in the chrome tanning process. In the vegetable tanning process, the skin is subjected to series of vats and agitated accompanied with progressive increase of tanning liquor. The vegetable tannins are basically made up of polyphenolic compounds which are divided into hydrolysable tannins and condensed tannins. In the finishing process, the chromium/vegetable tanned hides are frequently retanned to incorporate some desirable properties and textures including their colour, smoothness and filling in the hides. In addition, the excess amount of water is removed using the drying process, and consequently, it is cooled with cooling water. After retaining and drying, the crust is exposed to various completing tasks. The reason for these activities is to make the shroud milder and to veil little slip-ups. The cover-up is treated with a natural dissolvable or water-based colour and varnish. The completed final result has somewhere in the range from 66 to 85 wt% of dry issue [5].

4 Environmental and Chemical Concerns of Different Tannery Process The tannery procedure is majorly into three main stages such as pretanning, tanning and post-tanning process. In the pretanning process, several procedures such as soaking, liming, deliming, pickling and degreasing are done to the raw skin/hides. In this process, several chemical compounds such as pesticides and detergents are gushed out to the environment with the wastewater generated from the pretanning process. Further, the tanning process is divided into three major types such as vegetable tanning, chrome tanning and combined tanning. Various harmful salts such as chromium, zirconium and aluminium are used in the tanning process which are capable of creating various deleterious health effects and environmental concerns. Also, the formaldehyde, fish oil, silica and Calgon are gushed out of the wastewater generated by the tanning process. The oils are one of the main ingredients of the leather wastewater, and they are applied in the treated skins or hides subsequently. A combination of vegetable oil, sulphated oil, mineral oil, Epsom and glucose is used in the tanning process which is highly difficult to degrade in the tannery wastewater

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treatment. In the post-tanning process, the tanned leather is trimmed and conditioned into a fine leather. Furthermore, the final step of the leather processing is finishing method. Several resins, pigments, waxes and binders are utilized in the finishing process which are one of the hazardous waste in the environmental criteria [1]. Leather industries are one of the most elevated dangerous producers of toxic effluent per unit of output. The process of conversion of skin into leather is an intensely concentrated procedure using around 130 synthetic substances. The principle synthetics utilized in the different preparing stages incorporate lime powder, sodium sulphide, chromium sulphate, ammonium sulphate, sulphuric corrosive, formaldehyde, sulphonated and sulphated oils and colours. In the processing stages such as pretanning, tanning, wet finishing, drying and finishing process, the effluent gushing out of these processes is in the form of air, liquid and solid. Hydrogen sulphide and alkali are the significant gases discharged into the environment. Be that as it may, laboratory results indicated outflows lower than the national ecological quality measures. A large portion of the strong squanders are reused. The drums, containers and synthetic packs are obtained for reuse. Fleshing, crude cutting and buffing dust are purchased by cowhide board or poultry feed makers. Chromium is one of the most important chemical residues released in this tannery effluent which are highly carcinogenic and capable of causing various deleterious effects to human beings. Animal shavings are utilized as modest fuel in ovens causing the arrival of chromium into nature. The staying strong squanders are generally wrongfully dumped around the processing plant territory on unutilized lands. These strong squanders incorporate metal substance, for example, chromium, aluminium and zirconium, which detrimentally affect plant development. Over the span of preparing of cover-up into cowhide, approximately 50–150 l of water was utilized per one kilogram of changed over cowhide. In this manner, effluents released from tanneries are voluminous, profoundly hued, and contain an overwhelming residue load including lethal metallic mixes, synthetic concoctions, naturally oxidizable materials and enormous amounts of rotting suspended issue. Tannery effluents, with no pretreatment, are released unpredictably into water bodies or open land, coming about in tainting of surface just as subsurface water. The smelling salts outflow during the deliming cause bothering of the respiratory tracts. Other negative impacts of the alkali outflows incorporate the misfortune of land efficiency, impediment of the germination of plants and seeds, migraines, stomachaches, discombobulation, night visual impairment, sickness, dermatitis and other skin issues. Calfskin dust results in sensitivities and tumours that harm local people around the tanneries [9]. The research finding of Garai at 2014 is about the environmental aspects and health risks of leather tanning industry: A study in the Hazaribag area showed that the exploration discoveries uncover that the tannery business creates an unhygienic and poisonous condition in the Hazaribag region. Harmful substance and other lethal

Environmental and Chemical Issues in Tanneries …

7

squander results of the tannery business make air, smell, water and soil contamination, and so on which all seriously sway living conditions. The discoveries additionally show that 33% of respondents asserted a boundless and harsh scent as the primary issue; 37.5% referenced that grimy streets are the fundamental issue in the examination territory, on account of the business releasing squanders in an ill-advised way. Concerning untreated waste discharge, 35.6% said that the these spread different sorts of sickness (e.g., jaundice, the runs, skin infections), while 39.3% asserted that the severe smell in the region is added to an unhygienic condition for everyone [10]. Skin disease is one of the main problems caused due to the contamination of tannery wastewater in the water and soil. Based on the toxicity of the tannery wastewater, the extent of skin disease varies from minor rashes and itches to major skin cancer. More than 8000 labourers in the tanneries of Hazaribag experience the ill effects of gastrointestinal, dermatological and different maladies, and 90% of this populace kicks the bucket before the age of 50. The nearness of arsenic in the groundwater expanding shortage of crisp drinking water causes skin injury, kidney, liver inconvenience, malignant growth and so forth. The tannery workers did not wear any gloves, cover and uncommon shoes instead they work in exposed feet. The tannery squanders were arranged in spontaneous manner. These squanders fall in the nearby stream, and the ghettos’ individuals utilize this contaminated water and get various illnesses in them. These squanders secured the encompassing territory which makes noxious. The putrid condition damaged human well-being. The tannery wastewater negatively influenced the other sectors such as livestock growth, fisheries production and agricultural sectors causing various health disorders and damaging their lives. Shakir et al. in 2012 investigated the ecotoxicological risks associated with tannery effluent wastewater. The results showed that the hexavalent chromium and tannery wastewater have huge ecoharming potential, and significant levels of chromium are representing an impressive hazard to the human populace, aquaculture and agrarian industry that can pulverize biological system encompassing the tanneries [11].

5 Mitigation Measures Followed by the Tanneries Tannery effluents are viewed as an unconventional type of dirtied wastewater since they fluctuate across tanneries in both volumes just as in contamination load. 62 As such, every tannery presents it possess profluent issue. Along these lines, in any event, for a unique kind of cowhide, it is hard to figure a standard plan for emanating treatment. The strategies being used for the profluent treatment might be of a physical, concoction or organic nature, utilized either alone or in mix. A short record of a portion of these techniques utilized in the nation has just been accounted for above. Like all other modern wastewater treatment, the medication cost can be significantly decreased by embracing great in-house rehearses, measures identified with squander decrease at source and utilizing greater condition amicable advancements [9].

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From the findings of Azom and other researchers in 2012, some of the sustainable strategies are enunciated which can be used as effective mitigation measures in controlling the harmful effects of the tannery wastewater. They are as follows: • Transferring the tanneries from centre of the city to outskirts to avoid its negative impacts on the environment • Implementation of proper effluent treatment plant to eliminate the undesirable harmful toxins present in the tannery wastewater • Proper monitoring of the safety of the workers by providing protective aids such as masks, shoes and gloves • Examining the impacts of tannery effluent on the quality and richness of the soil with respect to physical and biological studies • Utilization of necessary chemicals in prescribed limit according to the Department of Environment • Proper management of the operation hours of the industry to reduce the negative effects of the tannery towards the habitat • Proper disposal of solid wastes consisting of toxic chemicals and undesirable solid wastes • Squanders utilized as poultry nourishment ought to be inspected previously as it is given to the poultry ranch, strong waste containing chromium that must not be utilized as poultry nourishment • Considering the financial part, minimal effort coagulant, for example, alum, lime and ferric chloride can be picked for the treatment of tannery effluents • Effective Environmental Management Plan (EMP) ought to be presented for most extreme contamination reduction. At long last, one might say that satisfactory preventive measures ought to be taken in tannery modern exercises with the end goal of guaranteeing sheltered, sound and sound condition for the more noteworthy advantage of our ecosystem [2]. Stream isolation is the underlying advance in executing in-plant controls. Because of the distinction in wastewater attributes from beamhouse (high pH and sulphides), tanning and retanning (low pH and chromium) tasks, increasingly proficient control could be accomplished through the utilization of a treatment procedure explicitly intended for the related contamination. Besides, the isolation could prompt the reuse or reusing of spent mixers and the recuperation of materials. Wastewater treatment is one of the major mitigation measures which can be used to reduce the negative impacts of the tannery effluent on the environment. Basically, three important treatment methods such as physical, chemical and biological treatment methods are applied in the elimination of hazardous compounds from the tannery industrial wastewater. The coagulation-flocculation is a first treatment step required to expel particulate material and different contaminations and also as chromium (VI), which hinders natural treatment. Essentially, to apply isolation of waste streams approach in tannery contamination anticipation is the most significant advance in spite of the fact that it is not broadly and essentially applied on the planet. Association of tanneries in the mechanical regions is another normal methodology which causes a lot to subside

Environmental and Chemical Issues in Tanneries …

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the contamination in corresponding to the reinforcing release limits. Anyway incorporated contamination counteraction procedure of the EU and the greening economy which incorporates the moving synthetic substances with the common ones, water minimization advancements and water reusing this segment will keep on spending endeavours for comprehending ecological issues [12].

6 Green Technology Benzene- and naphthalene sulphonates are generally applied in tanning of cover-up and sulpho-subordinates of naphthalene are seen in tannery wastewater at convergences of 0.1–30 mg L−1 . Naphthalene sulphonates and their subbed analogues have been accounted for to be inadequately degradable which was associated with either their atomic structure or their immediate harmfulness to potential microbial degrader. The sulphonated mixes in wastewater are known to be debased by a few bacterial consortia, yet the vast majority of the xenobiotic organosulphonates are dependent upon desulphonation. Ultrasound has been practised as an elective innovation to diminish synthetic concoctions use and calfskin quality. Synthetic adjustment of chromium tanning salt is one of the choices for improving the take-up of chromium. Manufactured tanning material dependent on chromium improved essentially (90%) chromium take-up. Chromium was complexed utilizing multifunctional polymeric grid. The substitution of ammonium salts in the deliming forms via carbon dioxide and the reuse of wastewater and synthetic compounds after layer filtration of the deliming/bating alcohol can be used as an effective alternative [12].

7 Conclusion Tanneries are seemed to be one of the highly pollution industries among the other commercial industries. In the conversion of raw skin to leather, various processing stages are involved such as preparation, pretanning, chemical tanning, vegetable tanning, wet finishing, drying and finishing procedures. Every processing stage of the tanneries consumes a huge amount of water and also releases toxic effluents with harmful chemicals and solvents. The disposal of these toxic tannery effluents without proper treatment into the environment can cause deleterious skin and respiratory issues, and also it causes tumours and organ damages. In environmental perspective, the release of tannery effluent into soil decreases the richness of the soil and also causes accumulation of toxic metal ions in the soil which spoils cause impotency of the soil nutrients. In addition, it also affects the livestock, fisheries and human beings in a larger scale. Several advancements have been made in the tannery wastewater treatment methodologies to obtain a sustainable and effective treatment of this effluent. Apart from the conventional methodologies, many new advancements such as membrane process, photocatalysis are implemented in the tannery

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effluent treatment. The minimization of water usage, reuse and recycle of wastewater in the various sectors of the leather processing stages can reduce the intensity of tannery effluents. Further implementation of green chemicals and solvents can reduce the toxicity of the tannery effluents and ease the treatment methodology. Thus, this chapter has clearly explained the various environmental and chemical issues of the tanneries, and it also clearly explains some of the mitigation measures which can be undertaken to reduce the severity of the tannery effluents.

References 1. Kavitha PR, Ganapathy GP (2015) Tannery process and its environmental impacts a case study: Vellore District, Tamil Nadu, India. J Chem Pharmaceut Sci 2. Azom MR, Mahmud K, Yahya SM, Sontu A, Himon SB (2012) Environmental impact assessment of tanneries: a case study of Hazaribag in Bangladesh. Int J Environ Sci Dev 3(2) 3. Ahmed IM (2015) Hazaribagh tanning area and pollution management. Department of Environmental Science, State University of Bangladesh, Dhaka 4. Jamal MT, Rahman S, Tasnim G, Farooq M, Zaki M (2017) Tannery industry 5. http://www.fao.org/3/X6114E/x6114e05.htm 6. Tinni SH, Islam MA, Fatima K, Ali MA (2014) Impact of tanneries waste disposal on environment in some selected areas of Dhaka City Corporation. J Environ Sci Nat Resour 7:149–156 7. Technical EIA guidance manual for skin/leather/hide processing industry. The Ministry of Environment and Forest, India 8. Rahaman A, Afroze JS, Bashar K, Ali MdF, Hosen MdR (2016) A Comparative study of heavy metal concentration in different layers of tannery vicinity soil and near agricultural soil. Am J Anal Chem 7:880–889 9. Khan SR, Khwaja MA, Khan AM, Ghani H, Kazmi S (1999) Environmental impacts and mitigation costs associated with cloth and leather exports from Pakistan. A report on trade and sustainable development submitted by Sustainable Development Policy Institute and IUCN-P to IISD Canada for the IISD/IUCN/IDRC project on building capacity for trade and sustainable development in developing countries, Islamabad 10. J. Garai (2014) Environmental aspects and health risks of leather tanning industry: a study in the Hazaribag area, Chinese Journal of Population Resources and Environment 11. Shakir L, Ejaz S, Ashraf M, Qureshi NA, Anjum AA, Iltaf I, Javeed A (2012) Ecotoxicological risks associated with tannery effluent wastewater. Environ Toxicol Pharmacol 34:180–191 12. Lofrano G, Meriç S, Zengin GE, Orhon D (2013) Chemical and biological treatment technologies for leather tannery chemicals and wastewaters: a review. Sci Total Environ 461–462:265–281

Leather in the Age of Sustainability: A Norm or Merely a Cherry on Top? Mukta Ramchandani and Ivan Coste-Maniere

Abstract In the area of fashion and luxury industry, there is a growing trend in consumer awareness when it comes to leather sustainability. The current chapter aims to understand and discuss for major leather users what is considered to be the major criteria for sustainable leather consumption. For example, vegan consumers refrain from buying animal-based leather but might indulge in using PU or PVC leather or other alternatives which could be ranking low in the sustainability criteria. The current chapter uses the primary data with an interview and secondary data from the industry assessments and industry cases which highlights what could be misleading for the buyers and producers. In addition, what are the perspectives of the manufacturers to develop newer sustainable methods of leather production, recycling needs and wastage are also discussed. Keywords Leather sustainability · Sustainable luxury · Sustainable fashion · Footwear sustainability · Sustainable consumption · Decision making · Sustainable production

1 Introduction How leather became synonymous with the luxury and fashion industry can be understood from its consumption patterns. The limited sourcing of the animal hides in the past, available only in the hands of the few, to the royals and the rich elites made it M. Ramchandani (B) UIBS, Zurich, Switzerland e-mail: [email protected] I. Coste-Maniere Luxury and Fashion Management SKEMA Business School, Sophia Antipolis, France e-mail: [email protected] Luxury and Fashion Management SKEMA Business School, Suzhou, China Global Luxury Management SKEMA Business School, Raleigh, USA Luxury Retail, LATAM, Florida International University, Miami, USA © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. S. Muthu (ed.), Leather and Footwear Sustainability, Textile Science and Clothing Technology, https://doi.org/10.1007/978-981-15-6296-9_2

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distinctively a symbol for differentiation and exclusivity. But currently, we live in the age of over-consumption which has driven the planet and its beings to the brims of extinction and irreversible damages. From the lens of sustainability, the description in the leather sector cannot just be limited to the animal vs. non-animal-based hides. But needs to be seen with a larger holistic viewpoint. It must as well include the aspects of humane ways of animal hides sourcing, production in limited quantities, bi-product of the food industry, the tanning of the raw hides to the final stage and the conditions of the workers coming in contact with the production. The current chapter presents the various points of assessments for the sustainability in the leather sector. Both manufacturer and consumer views of leather are included in the current chapter as we believe these must be considered for a deeper understanding of the subject as it can help determine the future. Our research was developed using various secondary and primary sources including an interview with a leather manufacturer in India. The manufacturing processes and the environmental impacts are a decisionmaking factor for companies using leather and also the consumers buying the leather products. Generally, the distinction made these days is on the basis of the tanning procedure, i.e., chromium-based tanning or vegetable tanning. The production processes of leather include curing, storage, sorting and trimming, dehairing and liming, fleshing, deliming and bating [1]. Post-tanning processes include the softening of the leather with oils and tanning agents to improve the feel and handling properties of the leather which further helps in coloring, lubricating and adding other characteristic properties like water repellence and oleophobicity [2]. The research by Laurenti et al. [2] suggests that when the life cycle assessment (LCA) is compared between the chromium-based leather and vegetable-tanned leather, it is important to consider that the vegetable tannins come from the trees (a renewable resource), whereas the chrome is mined and used once in leather. This aspect of how a fair comparison can be made between renewable natural materials and materials that come from fossil fuels or from one-time use of a mined resource is a major area which needs consideration. Furthermore, the impact categories need to be evaluated for such comparisons with toxicity. However, another consideration from our perspective should also be the effects of the production procedures on the workers working at these tanning factories and the hygiene practices, which could be different because the two tanning processes have different levels of the carcinogens and skin irritant chemicals. In the next sections of this chapter, we include the background on animal-based leather and non-animal-based leather, greener paradigms for consideration by manufacturers and brands, interview with a leather manufacturer, and key decision-making factors for leather consumers.

2 Methodology In order to understand the overall sustainable practices in the production and consumption, we gathered our literature from exploring various scientific research articles, reports and other publications, which included assessments of the previous

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literature as well. In the primary data, we have conducted an interview with a leather manufacturer based in Kanpur, India, to research in depth their view on key sustainable issues, pitfalls faced by a leather manufacturer and suggestions for the future.

3 Background Producing raw materials for the fashion and luxury industry comes along with damages to the environment, eco-systems and people. A major challenge in the race to be more profit-oriented fashion company and being sustainable at the same time stems from the fact that the textile industry is highly dependent on the use of chemicals, which are primary reasons for pollution and causing environmental degradation. It is not a new knowledge that a step toward a better sustainable future inclines toward the usage of sustainable long-lasting materials which cause minimal emissions in the environment. But when companies mislead the customers in the name of sustainability, it reflects poorly on the industry as such. Moreover, with the latest developed smart textile materials like bio-fabricated leather or synthetic leather look-alike, the quantitative data on the long-term environmental impacts is limited. Several claims of sustainability have lead users to believe that a company is sustainable. But what part of sustainable goals are these companies fulfilling is the question to be asked? Considering, for example, the usage of water as a resource in the textile industry, a heavy metal laden water bi-product used in the dying or washing process can be of adverse damage not only to the workers but also to the soil and groundwater basin. Affluent treatment plants would consider filtration of the water before discharging from the factories, but it requires better invigilation systems and checks. The next sections highlight some of the differences in the animal-based leather and non-animal-based leather.

3.1 Animal-Based Versus Non-animal-based “Leather” When it comes to leather, the basic norm in the consumption historically is related to the animal-based leather from the raw skin hide tanned to the usable conditions. In the past, the animal-based leather has been sourced from cattle-based animals like cows, goats and pigs as a subset of the bi-product from the meat industry. From the luxury sector, the animals not part of the popular food consumption innovated to exclusivity with the deriving leather from the animals like alligator, crocodile, snakes and ostrich. With the rampant unsustainable methods of sourcing animal hides, like torturous methods of killing the animals, the attention from luxury and exclusivity shifts more and more toward sustainability.

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• Oxymoron terms A report from Henkel [3] shows that the German leather industry (VDL) has been taking into consideration the misleading of the term “vegan leather” used by certain companies producing shoes, bags and furniture. As the term leather itself means coming from the animal, it cannot be used as a terminology for synthetic materials made of plastic petroleum based like PU and PVC leather. Vegan leather does not mean it is genuine leather, but what does it signify to the consumers? The VDL has accelerated their process of bringing into law the clear terminology for non-genuine leather. One good example is of Pinnatex which produces leather look-alike materials from the pineapple skins, setting a step forward in honest terminology. Obviating the use of the honest terminology and “synthetic leather” where ever applicable, adds to the greenwashing marketing elements of the consumers in the name of sustainability. • Cactus Leather One of the latest innovations in the non-animal-based leather sector has been the development of the cactus leather named Desserto. As per their website [4], Desserto is a highly sustainable plant-based vegan leather made from cactus, distinguished by its great softness at touch while offering a great performance for a wide variety of applications and complying with the most rigorous quality and environmental standards. Their aim is to offer cruelty-free, sustainable alternative, without any toxic chemicals, phthalates and PVC. It is also partially biodegradable and has the technical specifications required by the fashion, leather goods, furniture and even automotive industries. The company claims of using little amount of water for growing the cactus plantations using mainly the rainwater irrigation systems and every 6–8 months having a new harvest in the same plantation. The process induces less energy by using only the mature leaves of the cactus plant which are dried under the sun for few days to achieve the desirable humidity levels and does not use any herbicides or pesticides. • Fish leather The usage of the fish leather was traditionally by the indigenous heritage of the Arctic people, specifically the Inuit, Yup’ik and Athabascan of Alaska and Canada, in Siberia with the Nivkh and Nanai, the Ainu from the Hokkaido Island in Japan, Sakhalin Island Russia, the Hezhe from northeast China, and the people from Iceland [5]. The usage has now been taking into consideration for its sustainable features as more and more alternatives for sustainable leather are being researched. In particular, the highlights of the fish leather are that it does not require the resources or leave the carbon footprint associated with raising cattle and does not use endangered species that could threaten biodiversity. Mainly the salmon or cod from Iceland [6] is used or the pirarucu fish from Brazil, which is the staple food for the locals, and the skin is the bi-product of the food consumption. Its latest adaptation in the luxury sector can be seen in the Rick Ovens S/S20 collection [5].

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4 Production Procedure and Supplier Norms in the Leather Industry The tanning processes includes the chemical and mechanistic processes to transform the raw hides from the animals into a refined material used widely in different products like shoes, bags and upholstery furniture. But with respect to the environmental wastage, there exists bans and international restrictions for the export and import of the leather products. For instance, the European Union has banned the use of toxic chemicals in textiles and in leather with chromium VI. They promote the eco-friendly dyeing processes meaning that the chemicals that have the properties of being carcinogenic, mutagenic and toxic for reproduction or have metal complexes must be removed. Printing pastes cannot contain more than 5% volatile organic compounds, and chlorine bleaching is also prohibited [7]. The supplier stability is also a limiting factor for small- and medium-sized business in the leather sector. A lack of knowledge on the newer materials for the manufacturers could delay them in their supply. Suppliers are mostly driven by the demand in the market if the demand is for faster production of large quantities of the leather goods generated by the fast fashion brands. The suppliers do not have the capacity to cater to the sustainable leather like eco/vegetable tanned. Due to the fact that it takes longer to tan them compared to the chrome tanned leather. Additionally, when the sustainable leather does become available, the prices charged are much higher in comparison. Which also leads to the consumers lacking alternatives in the market for more sustainable consumption. In the shoes and bags production as well, it is not just about the type of leather used. In the shoes and bags production as well, the sustainability criteria must not be just limited to the type of leather used or the leather tanning procedure. But consideration of even the glue used in assembling the parts of the product must be sustainable and free from harmful chemicals. One problem is that the glue used when inhaled in humid or hot weather can be harmful to the worker’s health.

5 Greener Paradigms for Sustainability from Manufacturer/Brand Perspective It is crucial to understand where the sustainable actions from the brands and companies end up. To begin with this purpose, it must be clear to the brands what are the visions and goals for the future. The responsibility lies in the production and consumption phases. A brand can aim to be producing more sustainably but may be lacking in maintaining the sustainable consumption pattern, or vice-versa. Both of which can shape the path for benefits or destruction of the natural resources. In the first part of the paradigms, we describe the production, the second part describes the consumption, and the third part enriches the reader about the biodegradability aspect so that the leather product does go to landfills and minimize wastage.

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Additionally, there can be many facets to include in these paradigms like supply chain and it can be extended to further parameters, but our focus in the current chapter is to help the readers with some starting points in their complex decision-making factors for manufacturing. • Production Companies and brands producing materials and textiles for fashion must be responsible for their production processes to achieve their sustainability goals. Parameters like energy waste, harmful chemical emissions, wastage of water and other resources should be minimized. The use of harmful substances harms not only the workers involved in the production process but also the environment. For example, the use of heavy metals in textile dyes leads to the higher levels of toxicity. Other chemicals including alkylphenols, phthalates, formaldehyde, amines, etc., are hazardous to the environment [8]. In the production of new age smart raw materials, the life cycle assessments (LCA) must be considered in order to predict the long-term use of the leather and the resources required for its production. • Consumption It starts from the time the products are bought and starts to be utilized by the consumer. The duration of usage of the materials can last long or short depending on the frequency of usage, the quality and durability of the material, that is, for how long the produced material can be used and to what extent it will be intact in the long-term usage? The durability of natural materials like genuine leather is widely known to be long lasting in terms of different weather conditions, protection gear, atmospherics in the retail and storage environments. Therefore, the luxury and fashion brands must inform the consumers regarding the repairability of the materials. The consumption pattern for luxury consumers is different, where a high-end expensive material like silk or genuine leather is kept for decades and does not lose its value over time. Similarly, such long-lasting materials are the need of the hour to maintain the value of money and resources spent on producing textiles and the final product. As a company or a brand, it is important to also communicate effectively and be transparent about the sustainable practices so the end-user consumption can benefit and become more satisfied with the products purchased. As the demand for the new products will not be curbing down all of a sudden, the consumption to be sustainable should be a slow-paced process which needs to be dealt with inclusive of chemicals and processes that are organic and natural. • Biodegradability The aspect of biodegradability is very important one for the sustainable paradigms. Especially when the oceans are predicted to be having more plastics in the future than the fishes and the other marine organisms, it is vital to reduce the waste generated. Also as seen in certain reports about the fashion industry, the preconsumption wastage of unsold textile materials leading to the landfills every year is a major problem to be solved. Despite retail stores, giving high discounts and overseas shipping solutions, the problem still remains. One perspective that

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emerges as a solution is to tackle the need of newly produced materials and curbing the consumption levels in the society with the opportunities of recycled, upcycled and secondhand materials. But considerate to the fact that consumers especially who are fond of the luxury sector need more latest designs and exclusivity will not be leading the way for secondhand materials and their demand for new clothes.

6 Interview with a Leather Manufacturer The city of Kanpur in India is situated on the banks of the river Ganges and famous for its leather tanneries and exports to the American and the European markets. The leather industries in Kanpur were set up since the British colonial times in India to cater to the leather demands. As a result, boosted the economy of the city and the state but ended up being one of the highly polluted cities in the world and polluting the Ganges. We conducted an interview with one of the leather manufacturers in Kanpur Mr. Zafar Iqbal, to understand how the production side of leather aims to tackle the sustainability issue; below are the questions and answers from the interview conducted. Q1. What types of leather do you produce in your factory? We produce several types of leather: Vegetable-tanned leather used in the sole. Belting leather used in the production of belts and the watch sector. The third type is the industrial leather used in machines which is vegetable tanned. Next is the chrome tanned leather using fat liquors, syntans like phenolic, sulfone, protein, maleic, melamine, dicyandiamide, polypeptide and acrylic, glycerin, fish oils for softness mellowness, stretchable and color fastness specifically used in the footwear industry. Q2. Is vegetable-tanned leather used widely in shoes? Vegetable-tanned leather is used mainly for thinner and soft linings like the inner of the women’s shoes. Q3. What is in the sustainability/eco-friendly sector for the shoes sector? Following the government standards, we have to use the primary effluent treatment plant (ETP) at our factory meaning that the any non-diluted waste has to be stopped by us and not be discharged into the sewage. Our PH levels of the water initially are between 11 and 13 which is re-treated to be neutralized and reduced to the levels of 7–9. Then, from the ETP, the wastewater is discharged to common effluent treatment plant (CTP) which is from the government of India, where it again gets treated before finally being discharged. Q4. Yet why is it so polluted? It is not because of the leather sector that the Ganges is polluted, but because of the other industries which do not currently have as strict norms as the leather sector in Kanpur. The drainage system does not cater to the huge population of the city of 7 million people. Q5. What do you think of the latest innovative leather such as the pineapple skinbased leather, mushroom leather or the cork leather?

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In my opinion, it is merely for fashion shows and the trend. These types of leather cannot be for long-term practical use. Cork, for example, has been mainly used in the sole of the shoes as it has soft tissues. It is a different thing that they could use the cork on the shoe uppers in parts by gluing or other methods but for the entire shoe it cannot be as durable as the genuine leather. Practically for walking on streets or nature, the cork leather will not be able to withstand the roughness. It is merely a marketing and sales campaign for attraction to the cork leather in the shoes sector. Q6. What is your view of the recycling of genuine leather? The recycling in genuine leather or the recycled leather is no longer a genuine leather for me as the process converts it into something like a man-made leather which cannot be equivalent to the real form of the genuine leather. In textiles sector, it is possible as the raw materials can still be close to its original form but not in leather. Q7. What is the future of leather? Specifically for catering to the wastage? Like overproduction and overconsumption of leather goods? Natural resource like genuine leather should be used, and there should be a strict norm for amending the use of natural leather only in the shoes sector. As the animals are in the limited supply, the availability of the skins is scarce, which will make it more expensive and costlier making it into something more preserved and longer lasting. Consequently, it will minimize the consumption and people will use it with care to make it long lasting with the help of polish etc. This cannot be possible for a cheap pair of shoes. As the manufacturers keep producing the fake synthetic leather for shoes using much more harmful chemicals for processing. The preservability aspect of it besides the long-lasting impact will not be of importance to the consumers.

7 Environmental Assessments and Tests The life cycle assessment (LCA) is a tool used to evaluate the environmental impacts of products over their full life cycle, including resource extraction, production, use, transport and end-of-life (EoL) stages [9]. The certifications and test for leather are done for the assessment of the hazardous chemicals or substances like testing allergenic disperse dyes, nickel in metallic parts in contact with the skin and dimethyl fumarate, detecting banned azo dyes, incl. P-aminoazobenzene, pentachlorophenol (PCP), chromium VI and cadmium and for footwear test methods for the assessment of ecological criteria (EN 14602). According to Brugnoli and Král [10], there are numerous ways of calculating the LCA and product carbon footprint (PCF) in the leather sector but a harmonized way is necessary. Their research proposes that first the leather should be distinguished into one of the three considerations from the milk/meat industry: • co-product, • by-product,

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• waste. The methodology used in their report [10] included identification and analysis of existing standards and publications, selection of the reference standard (ISO DIS 14067) and analysis of the requirements of the reference standards (analysis of the different sectorial approaches and proposed harmonized methodology). In their analysis and detailed work, some of the key results included different actors of the leather values chain and guidelines for obtaining reliable leather PCF data. Furthermore, Brugnoli and Král [10], shared the following key elements which serve as the recommendation for the convergence and harmonization of the finished leather LCA and PCF: • Functional Unit: The functional unit in general should be measurable consistently, and it shall correspond to the basic unit that the tannery uses for trading the finished leather it produces; the proposal is to use, as functional unit, 1 m2 of finished leather (1 kg in the case of sole leather), including an indication of the thickness of the material. • System Boundaries: For the LCA and PCF of finished leather deriving from hides and skins which have been raised mainly for milk and/or meat production, it must start in the slaughterhouse, where the treatments are carried out to prepare the hides used in tanning and end at the exit gate of the tannery. • Quantification: The harmonized methodology proposed in order to obtain Kg of CO2e /m2 of finished leather, lies in the quantification of CO2e content of all the different products and material entering the tannery (upstream processes), adding CO2e produced in the tannery itself (core processes), as well as CO2e emanating from water and air purification and waste recycling/disposal (downstream processes). • Allocation: In the leather making process, allocation shall be avoided whenever possible and, if unavoidable, it should be made according to the physical relationship within the single process under consideration.

8 Decision-Making Factors by Consumers According to an interview reported in the research by Streit and Davies [11], the consumers for luxury goods do not consider “ethics” to be the priority factor for purchases. In addition, if a luxury product is ethical it is perceived more like a bonus factor from the brand. Their research also reported that luxury brands in general are perceived to be ethical by consumers, but it could be a beneficial factor for the consumers to know more if the brands would share more information about the material productions and supply chain. Several other researches have been done in understanding the types of consumers for the purchase of sustainable luxury fashion goods such as prosocial behavior, status consumption, costly signal theory, ecoconspicuous and eco-conscious consumption [12].

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Fig. 1 Search and decision-making factors for purchase of sustainable leather products

From our research and experience in this sector, we propose that the following factors (Fig. 1) will help in understanding the consumer’s search for sustainable leather product and decision making for the purchase: 1. Price: The leather product shoes/bags/apparel, etc., are subjective to price sensitivity level of each individual consumer. However, the more sustainably compliant the brand is, the prices charged tend to get higher. From the standpoint of financial consideration of purchasing leather, customers searching for high-quality genuine leather also associate the high prices for the quality and longevity. However, when it comes to bio-fabricated substitutes of leather, the prices do not justify the quality for majority of customers. 2. Purpose: If the product is bought for the purpose of outdoors or indoors. For example, the leather safety shoes worn by workers everyday ascertain the safety regulation vs. leather shoes meant for occasional use or indoor work. 3. Type of leather: Natural genuine animal leather or bio-fabricated synthetic leather look-alike which may mislead the consumers to an extent. Scarce leather sourced from crocodile, snakes, ostrich and others qualify for the higher prices due to the limited supply. 4. Certifications and tests: The buyers of the raw materials from factories-based overseas should not just solely rely on certifications which are given to the large firms and factories but must try to inculcate the small manufacturers and small suppliers overseas. Sometimes the certifications can be misleading as not all firms practice and adhere to the norms laid by the certificating companies, and one example is the case of Rana Plaza collapse where the manufacturing unit also claimed to have had certifications for better working conditions. By inculcating small manufacturer those who cannot afford the hefty fees of certifications, it becomes more a responsibility to further check and invigilation in terms of keeping regular and maintaining records of the safe working conditions of employees at the production houses, the hygiene standards, the wages paid and

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impact on the people. Which naturally could be a time-consuming process but yields better sustainable results in the long term. 5. Place of production: Once the primary decisional considerations are made by the consumer based on the above factors, the place of production can play an important role. For example, there is a general notion in the European and American consumers of products being of inferior quality if made in Asia vs. made in Europe or USA [13]. Albeit many of the leather products claiming to be made in Europe are in fact partially or fully produced in Asia.

9 Discussion Conclusively, from our research, we find that the leather production cycles must be limited for supply of quantities but higher in quality following the environmental regulations, be inclusive of having the fair price model than a mere high profitoriented model. In addition, the manufacturers need to be more proactive on taking a lead for innovation of sustainable production methods of high-quality leather and not be dependent just on the market demand, i.e., being more a market driving company and taking the lead than be driven just by the market. They must no longer be ignorant of the high need for more sustainable reforms and LCA assessments of their different stages of the leather production. There is a higher possibility for the leather industry to emerge as a role model sustainable material due to its longevity, repairability and biodegradability compared to the other materials. In addition, the brands should not mislead the consumers and use the honest terminology. For the consumers, the more the awareness and education on the materials used by the brands, the more sustainable consumption can emerge, which is a necessary step to promote the slow fashion and a holistically sustainable maintenance and innovation of the leather industry. Nevertheless, it is difficult and complex to have a perfect system of sustainable leather production and consumption, but the future lies in the hands of those who can create the innovative technologies which is less evil and pave the way for better environmental preservation.

References 1. Black M, Canova M, Rydin S, Scalet BM, Roudier S, Sancho LD (2013) Best available techniques (BAT) reference document for the tanning of hides and skins. JRC 83005. EUR 26130 EN. ISBN 978-92-79-32947-0 (pdf). European Commission; Joint Research Centre; Institute for Prospective Technological Studies, Seville, Spain 2. Laurenti R, Redwood M, Puig R, Frostell B (2017) Measuring the environmental footprint of leather processing technologies. J Ind Ecol 21:1180–1187. https://doi.org/10.1111/jiec.12504 3. Henkel R (2019) Is the’vegan leather’ label misleading consumers? https://fashionunited. uk/news/fashion/are-manufacturers-misleading-consumers-using-the-label-vegan-leather/201 9102845933 4. Desserto (2020) https://desserto.com.mx/desserto

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5. Mallon J (2019) Is fish skin the new frontier for eco-friendly fashion? https://fashionunited.uk/ news/fashion/is-fish-skin-the-new-frontier-for-eco-friendly-fashion/2019110546042 6. Atlantic Leather (2020) http://www.atlanticleather.is 7. European Commision Eco-Label. https://ec.europa.eu/environment/ecolabel/digital_toolkit. html 8. Rozas AC (2017) Textile toxicity: what lurks in your clothes. Retrieved from https://fashionun ited.uk/news/fashion/textile-toxicity-what-lurks-in-your-clothes/2017061424828. Retrieved on 2 Aug 2019 9. ISO (International Organization for Standardization) (2006) ISO 14040:2006: environmental management—life cycle assessment—principles and framework. International Organization for Standardization, Geneva, Switzerland 10. Brugnoli F, Kráˇl I (2012) Life cycle assessment, carbon footprint in leather processing (review of methodologies and recommendations for harmonization). In: Eighteenth session of the leather and leather products industry panel, UNIDO. https://leatherpanel.org/sites/default/files/public ations-attachments/lca_carbonfootprint_lpm2012.pdf 11. Streit CM, Davis IA (2013) Sustainability isn’t sexy an exploratory study into luxury fashion. In: Gardetti MA, Torres AL (eds) Sustainability in fashion and textiles: values, design, production and consumption. Greenleaf Publishing Limited, Sheffield 12. Ramchandani M, Coste-Manière I (2018) Eco-conspicuous versus eco-conscious consumption: co-creating a new definition of luxury and fashion. https://doi.org/10.1007/978-981-10-828 5-6_1 13. DW (2020) https://www.dw.com/en/luxury-behind-the-mirror/av-51115721

Blockchain Technology in Footwear Supply Chain Hao Cui and Karen K. Leonas

Abstract This research investigated how adopting blockchain technology will strategically place footwear companies in a competitive market. The article attempted to answer three central research questions: (1) Should a footwear company adopt blockchain technology in its supply chain? (2) What can footwear companies gain from the adoption? (3) Where can the blockchain position the footwear companies in the competitive market if the implementation of the technology is in the supply chain? First, we explored the business model and the features of the footwear industry and examined the blockchain technology, which provided the information from the characteristics of the industry and the advantages of the technology as the inputs of the TOWS matrix. Next, the author highlighted what benefits the footwear companies could get from the adoption of the technology based on the TOWS matrix analysis. Also, the author analyzed where the blockchain would position the company if the adoption of the technology is in the supply chain by investigating the definition and characteristics of the disruptive technology and Roger’s diffusion of innovations theory. Finally, the author concluded that technology still holds for promise though the implementation of the technology has several barriers and challenges, given the potential of the technology. In terms of the scope of this research, this chapter focused on catering to the needs of footwear giants (i.e., Nike, Adidas) due to their urgent needs of creating a transparent and traceable supply chain. Keywords Blockchain · Footwear · Supply chain · TOWS matrix · Diffusion of innovations · Disruptive technology · Transparency and traceability · Competitive position

H. Cui Wilson College of Textiles, North Carolina State University, Raleigh, NC, USA e-mail: [email protected] K. K. Leonas (B) Textile and Apparel, Technology and Management, Wilson College of Textiles, North Carolina State University, Raleigh, NC, USA e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. S. Muthu (ed.), Leather and Footwear Sustainability, Textile Science and Clothing Technology, https://doi.org/10.1007/978-981-15-6296-9_3

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1 Introduction 1.1 Background Consider this scenario: When you walk into a fashion store, you pick up one RoundedToe Pump made in Vietnam. You like the style and color and decide to bring it back to your shoe rack. If someone told you that this product is a knockoff and was manufactured in a sweatshop that has been discharging tons of hazardous wastewater into the local river, would you still purchase this product? This billion dollar question bothers most of the footwear companies because of the customers’ concerns about buying the counterfeit product and increasingly awareness of the importance of sustainable/responsible purchases. According to Muthu [36], the production of the footwear products poses a negative impact on the environment in several ways, given the resources used, energy consumed, and wastes generated in the life cycle of the product. Doorey [11] further indicated that social factors such as working conditions in the manufactures could affect consumers’ decisions over their apparel and footwear. In response to these impacts and concerns from the consumers, most of the apparel and footwear brands have committed to follow up United Nations Sustainable Development Goals (UNSDGs), which could support brands to mitigate social and environmental impact throughout their value chain. Some sustainability pioneers even have gone beyond this commitment and have been starting setting up science-based targets (SBTi) and goals such as zero discharge of hazardous chemicals (ZDHC) to tackle more environmental issues such as climate change and the toxicity released from the environment. However, scholars and sustainability practitioners have reprimanded that these apparel and footwear brands are just considering sustainability as one of the elements in companies’ public relations strategies [29]. That is to say, the brands and retailers are just making commitments and setting up goals to be in favor of their Greenwashing Public Relation (PR) strategies and therefore boost their sales accordingly. Apart from the social and environmental issues, the apparel and footwear industries are also urgently working on addressing the fake product issue given the products are easily being imitated. Carpenter and Edwards [6] found out that the counterfeit products did threaten the manufacturers and retailers of originator products. According to [31], the amount of counterfeit goods and fake products has skyrocketed thanks to the trends of globalization and online shopping. It is no doubt that fake products could undermine the brands’ intellectual property rights and even the brands’ reputation by compromising the quality of the knockoff products. Although brands are using a variety of product authentication verification methods (i.e., hidden printed messages, color-shifting inks, etc.) and adopting new product tracking and tracing technologies (i.e., radio-frequency identification, barcodes, etc.), the knockoff manufacturers, however, could always find a way to avert these methods and technologies. The recent “breakup” between Amazon Inc. and Nike Inc. is another solid evidence of the severities of the knockoff issue. In response to the sustainability and counterfeit issues, what actions footwear giants such as Nike Inc. and Adidas AG should take to convince their customers that

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they are buying the authentical products and making conscious decisions? According to Doorey [11], information disclosure could mitigate the social sustainability impact from the supply chain, address the forced labor issues, and improve labor practices. James and Montgomery [21] also identify the consumers’ demand for the sharing of information throughout the supply chain from apparel and footwear retailers [21]. In the meantime, the industry is foreseeing a trend to go beyond auditing, look beyond the first-tier manufacturers, integrate sustainability to core business practices, and bring transparency to the supply chain [23]. Several papers and researches also back up the trend and customers’ needs for information disclosure, highlighting the importance of creating transparent and traceable apparel and footwear supply chain [24]. There is one shared keyword in these researches: information disclosure. Information disclosure renders the brands to build a transparent and traceable supply chain and therefore convinces customers that they are making a sustainable and conscious decision. Information disclosure is not only mitigating social and environmental impact throughout the supply chain but also addressing the counterfeit product issues by creating a traceable supply chain. Li [31] identified the potential of adopting tracking technology to disclose the production information throughout its entire supply chain and therefore secure the authenticity of the products. Due to the important role of information disclosure throughout the supply chain, this research will explore how footwear giants could unveil the “opaque cover” of their supply chain in the rest sections of this article. This chapter started off with the background of the importance of creating a transparent and traceable supply chain for the footwear industry and chose the technology that has the potential to address the issue. Next, we discuss the objectives and methods we used in this chapter. Then, we presented a brief introduction to the footwear industry and blockchain technology. In the following section, we analyzed what benefits could bring to the supply chain and what competitive position could bring to footwear companies by adopting the technology. The section following this investigates the application cases and barriers of the technology. The final section wrapped up with the conclusion and future suggestions on the adoption.

1.2 Available Technologies and Tools The researchers will highlight three different technologies and tools: radio-frequency identification (RFID), Higg index, and blockchain to answer the question on creating a transparent supply chain. After the brief introduction on these three technologies and tools, the researchers will further compare them from different perspectives and find out what technology would fit in the footwear supply chain and address the emergency of information disclosure.

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Radio-Frequency Identification (RFID)

Radio-frequency identification (RFID) could automatically identify and track tags where digital information is electronically encoded [51]. According to Kwok and Wu [28] and Li and Zhao [30], RFID makes the textile supply chain—from raw material production to garment production—more transparent and traceable and improves the productivity throughout the supply chain. Kwok and Wu [28], Li and Zhao [30], and Bhagwat [2] listed several benefits and challenges of adopting the technology throughout the supply chain. In terms of the benefits, the technology could provide real-time inventory data and reduce the error and cost in terms of the wrong data-based decision. However, the technology has one significant flow in terms of data security, where the data generated from the technology is mutable and easily tampered by either external or internal parties.

1.2.2

Higg Index

Higg index is a tool to measure the sustainability performance of brands and manufacturers in the apparel and footwear industry based on the explanation of the Sustainable Apparel Coalition (SAC),1 the creator of the Higg index. Lou and Cao [32] also provided a more comprehensive explanation regarding the Higg index and stated that it could help the participants to compare their sustainability-related performances among the peers in the industry and guide the customers to make the eco-conscious and social-conscious choice. When it comes to the supply chain and production, Higg material index and Higg facility index could help the decision-makers in the retailers to capture the social and environmental impact of a product from raw material extraction to final product manufacturing.

1.2.3

Higg Material Sustainability Index

Higg material sustainability index analyzes the environmental impacts that are categorized into different classification and renders the target audiences look at the ecorelated issues derived from the materials from a different perspective. The Higg material index will walk the audiences through five main environmental impacts, most related impacts related to the apparel and footwear industry, namely global warming, eutrophication, water scarcity, abiotic depletion potential, and chemistry (see Table 1). The Higg material sustainability index could help the decision-makers to choose the right materials based on their sustainability agenda. For example, brands who are prioritizing tacking the chemistry and climate change issues could select

1 Sustainable

Apparel Coalition: is the apparel, footwear, and textile industry’s leading alliance for sustainable production. Source: https://apparelcoalition.org/the-sac/.

Blockchain Technology in Footwear Supply Chain Table 1 Explanation and examples of the five environmental impact categories

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Environmental impact Definitions Global warming

The effect leads to climate change

Eutrophication

Excessive richness of nutrients in a lake or other body of water

Water scarcity

Excessive use of water resources leads to the lack of the water

ADP

Depletion of non-renewable resources, i.e., fossil

Chemistry

The hazardous chemicals used in the production processes

Sources Adapted from https://apparelcoalition.org/the-sac/

the materials with less impact on chemistry and global warming potential for their material extraction processes.

1.2.4

Higg Facility Index

Higg facility index provides a tool for manufactures (i.e., tanneries, material mills, and shoe manufacturers) to evaluate and quantify the sustainability performance of their manufacturing units. The manufacturers are required to conduct self-assessment by filling out the questionnaire from the Higg facility module covering both environmental and social topics. The environmental module covers topics such as energy and water usage and environmental management system while the social part includes topics in terms of recruitment and hiring, wage and working hours, and health and safety, etc. The normalized results will be used as a benchmark for manufacturers to compare the social and environmental performance against those from their peers.

1.2.5

Blockchain

Blockchain is a digital ledger with blocks of information linked together. Each party on a blockchain has access to all the information, and no single person or entity controls a blockchain. Because each block of data (transactions) is linked to all previous ones (“forming the chain”), unlike the radio-frequency identification (RFID), the blockchain is immutable [50]. Although this technology is deployed mostly in the financial sector, there is a huge potential of adopting this technology in the supply chain to address transparency and traceability issues in the supply chain. Accordingly, blockchain offers several advantages for sustainability performance and tracking in supply chain management with some accompanying barriers [26].

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Benefits of blockchain: • Recording and validating transactions efficiently and permanently (e.g., selfexecuting contracts); • Auditing of all transactions (an audit trail that cannot be altered); • Tracking time and location of actions; • Reducing the risk of data loss or fraud; • Exerting pressure on supply chain partners toward greater accountability; and • Providing immediate access to transactions occurring in the supply chain. Barriers of blockchain: • Differences of laws, regulations, jurisdictions, and institutions across a global supply chain; • Collaboration among all relevant parties; and • Implementation of technology-based solutions for suppliers, both in developed and developing countries.

1.3 Comparison Among Different Technologies In this section, the research compares the three technologies and methods from six perspectives: (1) transparency (2) traceability (3) speed (4) security (5) compatibility (6) cost. 1. Transparency: The information evaluates how the data could be disclosed transparently as per request. In other words, the original data is available when needed. 2. Traceability: The data throughout the supply chain could be tracked down and verified. Consumers could dig into the details about how the product is made (i.e., the raw materials, manufacturers’ info). 3. Speed: Real-time data could be captured; it also assesses the time needed for interactions and communications . How long the data could be processed and obtained throughout the system? 4. Security: This information shows if the technology could secure the cybersecurity of the data. That is to say; the data is not being able to be hampered and hacked. 5. Compatibility: This perspective evaluates if the technology is easily integrated into the system. Are there any skillsets workforce should have if the new system is introduced? 6. Cost: The cost of the installation of the system and of maintenance and operation for the system. Table 2 analyzes the performance of these six perspectives for the three technologies. Following literature provided the author with the hints of creating this table [2, 28, 26, 30, 32, 50] and the author’s frontline working experience in the supply chain. Matrix A presents the measurement of performance from these six perspectives for the three technologies based on above analysis. i represents the number of the

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Table 2 Performance dimension of these technologies in the supply chain Performance dimension Blockchain

RFID

Higg index

Transparency

Information could be uncovered, and the original data is accessible when needed

Information could be uncovered, and the original data is accessible when needed

Information could be uncovered, and the original data is accessible when needed

Traceability

The data throughout the supply chain could be tracked down and verified. Consumers could dig into the details about how the product is made (i.e., the raw materials, manufacturers’ info)

The data throughout the supply chain could be tracked down and verified. However, the data needs to be verified through addition steps given the data is easily being hampered at facility level

The Higg index is not able to track down all the information through the entire life cycle of the product due to the data collection methods. In addition, the data needs to be further verified and audited

Speed

Real-time data could be captured. With the integration of IoT devices, the time for interactions and communications will be brief. The data could be processed and obtained immediately throughout the system as per request

Real-time data could be captured through RFID devices and chips. However, it will take time for data to be communicated between the RFID hardware and the ERP system the facility is using. The physical limitation, such as Internet bandwidths, will also have an impact on the quality and speed of the interaction

Real-time data could not be captured through the Higg index. The data will be submitted manually by the facilities manager

Security

The data is immutable. The hackers are rarely able to hack the data given the existing computing power most hackers have

The data is easily being hampered. Without the protection mechanism, the data is also easily being hacked

The data is easily being hampered and hacked (Given all the information is stored in the server provided by SAC)

Compatibility

With the Internet of things (IoT) devices and blockchain platform, the technology is easily integrated within the existing supply chain system. However, the full deployment of the technology needs the workforce who has the knowledge of blockchain platform and IoT devices. The compatibility of the blockchain is quite similar to other two technologies

Most of the wireless communication hardware for RFID could be seamlessly integrated into the production line. However, the system needs technicians who could work on extracting the data from the software and understand how to maintain the RFID devices and chips

No additional devices will be integrated into the system. However, in some cases, it will require the facilities to have sensors or electronic devices to collect the data. The system needs experienced experts who can conduct the self-assessment for the facility

(continued)

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Table 2 (continued) Performance dimension Blockchain

RFID

Higg index

Cost

The cost of the RFID consists mostly of hardware such as wireless communication devices and chips and software. Given the development of technology, the cost of the hardware has been reduced these years, and the cost will be lower than the blockchain

Higg index does not require any hardware devices, though the self-assessment does need the educated workforce to finish the Higg index. In addition, the self-assessed data needs to be verified through external audits. The cost of human resources and verification of the results will make it much higher than RFID, maybe in some cases higher than blockchain

Although the cost of generating blockchain digital certification by using the existing platform will be low (i.e., IBM and AWS blockchain platform), the cost for installment and maintenance and operation of the IoT devices and sensors which provide the data to the digital ledger could be high. Thus, the cost is comparatively higher than RFID and Higg index

row of the matrix which refers to technologies (blockchain, RFID, Higg index) while j represents the number of the column of the matrix which refers to the six aspects (transparency, traceability, speed, security, compatibility, and cost). aij stands for the measurements of the performance for assigned technology in particular aspects (i.e., a11 represents the measurement of the performance for blockchain from transparency perspective). All the measurements are on a scale from 1 to 5. 1 means very bad, while 5 indicates very good performance in the aspect. Y i is the sum of all the measurements for a particular technology without assigning any weight to each perspective. ⎡

⎤ 555541 A = ⎣5 4 3 2 4 3⎦ 531142 Matrix A is the measurement of the performance Y1 =

6 

a1 j = 25

(1)

a2 j = 21

(2)

a3 j = 16

(3)

1

Y2 =

6  1

Y3 =

6  1

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Equations (1)–(3) represent the calculation methods of the measurement of the performance of three technologies based on the six evaluation metrics mentioned above. Based on the above calculation, the blockchain stands out among three technologies. Thus, next, this research focused on exploring the blockchain technology and figure out how blockchain could be used in the context of the footwear supply chain.

2 Objective and Method 2.1 Objective In this chapter, the author attempts to answer a central question: Should footwear companies adopt blockchain technology in its supply chain? Two sub-questions revolved around the central question are raised and explained in the following sections, including (1) What can the footwear companies gain from the adoption? (2) Where can the blockchain position these companies in the competitive market if the implementation of the technology is throughout the companies’ supply chain? The explanation of questions could facilitate the audiences to understand why blockchain technology could address the issues that footwear companies are facing and how early adopters could stand out among their peers and competitors.

2.2 Method To elucidate these research questions, the authors analyzed the overview of the footwear industry, including the industry characteristics, production processes of footwear, and the supply chain structures and the challenges throughout the supply chain. In the next section, the research delved into the topics on what is the blockchain technology and how blockchain technology could address the issues throughout the supply chain. The study then looked into the key terms and popular blockchain services and frameworks. The research concluded this section by analyzing what benefits this technology could bring to the supply chain. After exploring the blockchain technology, authors cracked the gains from the adoption of the technology by analyzing outputs from the threats, opportunity, weakness, and strength (TOWS) matrix. Following the TOWS analysis, this study defined the strategic position in which the footwear companies will be by exploring the definitions of disruptive technology and theories of diffusion of innovations. The authors then investigated the applicable area of this technology and picked three examples of how this technology has supported supply chains in other industries. Finally, the authors explored the challenges most of the footwear companies will be facing and the potentials of this technology if these companies adopt the technology before concluding this

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study with the author’s recommendation on whether footwear giants should adopt this technology throughout the supply chain and what this technology could bring to the company.

3 Footwear Industry Mapping 3.1 Footwear Industry Overview Apparel and footwear industry is a globalizing and myriad industry that employs millions of people internationally [17]. A market report from Credence Research Inc. revealed that global footwear market value was at US 222.4 Bn in 2017 and expected to grow by about 31% in the following decade [8]. 222 Bn is almost equivalent to onesixth of the Australian GDP in 2017. This report shows the increase in demands in both athletic and non-athletic shoes. The report also indicated there are several global footwear market leaders, including Adidas AG, Nike Inc., Bata Limited, Puma SE, VF Corporation, New Balance Athletics, Inc., The Columbia Sportswear Company, etc. [8]. Given the companies’ size and global influences, this sector compared three key payers among the worldwide footwear market leaders: Nike Inc., Adidas AG, and VF Corporation (see Table 3). These three companies are good examples of globalizing and myriad businesses mentioned in the literature. Specifically, these three companies took up 40% revenue of the footwear market, hired around 170,000 employees globally, and established a decentralized and globalized supply chain. Although all the companies Table 3 Comparison among three market leaders Nike Inc.

Adidas AG

VF Corporation

Revenue 2018 (USD) (Bn)

36.39

23.78

13.8

Employees 2019

73,100

57,016

50,000

Headquarters

Beaverton, Oregon, USA

Herzogenaurach, Germany

Denver, Colorado, USA

Global supply chain

Yes

Yes

Yes

Focus area in sustainability

Transparent supply chain and circular economy design

Circular economy design

Traceable and transparent supply chain

Climate commitment

Science-based targets set

Science-based targets committed

Science-based targets set

Source NIKE Revenue 2006–2018 | NKE Retrieved from www.macrotrends.net Adidas AG annual report 2019, VF Corporation annual report 2019, Nike Impact report 2019, VF corporation sustainability report 2019, Adidas AG sustainability report 2019

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have committed to mitigating their social and environmental impact, each has very different sustainability agendas. For example, Nike committed to creating a traceable and transparent supply chain with the aid of big data. Adidas AG has focused on designing eco-friendly products with the introduction of the novel plant-based material. VF also allocated resources to make their supply chain more traceable and transparent; however, they are paying more attention to the social realm topics such as forced labor and fair wages. When it comes to the spectrum of the retailing side, the footwear industry is also experiencing growth in demand due to the “fast fashion” effect. The idea of “fast fashion” was originally derived from the “Just-in-time” manufacturing philosophy and quick response strategies [35]. According to Morgan and Birtwistle [35], “fast fashion” companies could bring new styles from design to shop floor within as short as two weeks. Although “fast fashion” giants such as INDITEX Group (parent company of ZARA) and H&M Group never explicitly admit they are “fast fashion” company, they are the pioneers of adopting “Just-in-time” and “Quick Response Strategies.” The pioneers of the fast fashion industry embrace this idea to satiate the appetite of fashion-hungry consumers wanting to buy items in new trends as they appear [35]. “Fast fashion” retailers, such as H&M, Zara, Primark, and TopShop, provide products that are designed to be worn less than ten times in the life cycle of the product at very competitive prices in the market. This characteristic of “fast fashion” has directed consumers to purchase and disposing of ever larger quantities of apparel and footwear [33, 35]. The low-price strategy and huge demand require a decentralized manufacturing and marketing strategy. The traditional footwear companies (Nike, VF, Adidas, etc.) have been catching up with their retailing competitors by adopting this “fast fashion” idea. Besides the footwear companies embracing the concept of “fast fashion,” the industry also sees a trend of sustainable consumption. Morgan and Birtwistle [35] declared that the sustainability concerns of the apparel and footwear industry have come to public awareness since the 1990s. Unlike the older generation, the younger generation—especially Gen Y and Gen Z—has been paying more attention to both social and environmental sustainability other than only focusing on the styles, quality, and price of the products. In response to customers’ preference over sustainability, most of the apparel and footwear companies have made commitments to mitigate their impact (i.e., setting up science-based targets) and introduce the new materials and designs which are considered to be beneficial to our ecosystem. Finally, Nash [39] recently conducted a study showing how social media platforms are influencing the purchase decision of the generation Y and generation Z—target customers of apparel and footwear products. Given the increasing power of the social media platform, even scandals (i.e., Bangaladesh building collapse and Chinese worker strikes) in the remote supply chain may have the ripple effect of the entire brand. 2013 Dhaka garment factory collapse has led to several boycotts toward some US and EU retailers because this information has been spread and gone viral on the Internet and social media. Thus, footwear retailers should prevent these scandals from happening throughout their entire supply chain. Otherwise, the power of this

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new media could corrupt the reputation and image of the company and, therefore, debase the profit.

3.2 Footwear Production Have you ever wondered how your shoes that you will be wearing every day are made? Given the mixture of types and styles of shoes, there are hundreds of different production processes due to the different designs and materials. But, in this study, we will focus on figuring out the production processes for sneakers and fashion shoes, given our target companies for this study (i.e., Nike Inc. Adidas AG). Normally, one pair of sneakers started his life cycle from preparation processes. During this process, the shoe last (shoe shape) will be made of plastic, wood, or metal, and the shoe pattern will be designed. Then, this pair of shoes will move to the cutting process where all the pattern parts for the shoe upper will be cut in a variety of ways (computer-controlled cutter, laser cutter, or hand cutting, etc.). Once all parts and components are prepared, the stitching lines—usually consists of 30–50 workers— will stitch and assemble the parts all together and attach the shoe upper onto the sole. Before this pair of sneakers ending up lying inside the package, the shoes will experience the last process where the workers will pull the upper from the last (shoe shape) made previously and make it the real shape of a shoe. Finally, the pair of sneakers will be quality checked before being packaged in the shoe box. Subic et al. [47] summarized these production processes and classified all the production processes into two categorizations: tier 1 manufacturing and tier 2 manufacturing. Most of the components and accessories will be prepared in the tier 2 process (mold injection, shoelace production, etc.). Once all the components are being prepared, all these parts will be cut, stitched, assembled, finished, and being packaged for final shipping in the tier 1 manufacturers. Like the apparel sector, footwear production also poses social and health threats to workers and environmental perils to our ecosystem. Rajnarayan [43] illustrated several concerns, such as occupational injuries, child labor, chemical hazard, and forced labor that are related to the footwear production processes. For example, the hazardous chemicals used in the gluing process will cause the severe health issues of the workers and even the life of them in some cases. Irresponsible suppliers were using child labor and forced labor to produce shoes for well-known western footwear companies. All these types of scandals will no doubt cost the reputation damage of these companies due to the misconduct or wrongdoings from their suppliers.

3.3 The Footwear Supply Chain As mentioned earlier, the trend of “pursuit of fast fashion” requires a decentralized and globalized manufacturing strategy for the industry. Also, according to Muthu

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[37], the apparel and footwear supply chain is very complex due to the wide spectrum of the products. Given this manufacturing strategy and complex features of the entire supply chain, the supply chain of the industry is highly decentralized and globalized, and most apparel and footwear companies rely on outsourcing and subcontracting services of its production [17]. The footwear giants (i.e., Nike Inc., Adidas AG) are good examples of dependence on outsourcing and subcontracting because they do not even own one factory to make the sample product. For example, Nike has most of the sneaker factories in Southeast Asia, while most of the accessories and components factories in East Asia. The high decentralization and globalization are the recipe for the low price of the footwear products because such sourcing strategy has created a highly competitive manufacturing environment, and thereby, the cost could be reduced dramatically. The increased labor cost in the mature production market (i.e., China and Vietnam) has also encouraged the footwear companies to source in the countries with lower cost (i.e., Myanmar, Bangladesh). All these factors fast response market strategies, diversified products, and components and low-cost sourcing plans drove the footwear companies to decentralize their supply chain in almost all continents of the world.

3.4 Challenges Throughout Supply Chain Given the nature of the footwear decentralized supply chain and the risks existing in the production processes, there are several issues that the industry is facing throughout the supply chain: (1) social and environmental concerns; (2) transparency and traceability demands; (3) counterfeit products and quality.

3.4.1

Social/Environmental Concerns

According to Boström and Karlsson [3], the apparel and footwear industry poses social threats, given the complexity in the supply chain side of the industry. Forced labor, child labor, and other occupational health issues could be the potential social problems identified throughout the extended and decentralized supply chain. For example, it will pose serious threats to the health of the relevant workers who are involved in these processes due to the improper use of hazardous chemicals without personal protection equipment, the inappropriate store, and disposal of these chemicals. The recent investigation regarding forced labor issues identified in Chinese suppliers has jeopardized most brands’ reputation and images. Rana Plaza collapse in Bangladesh is another example, which has called most brands and consumers’ attention to sustainability [10]. The industry also causes environmental problems because of the resources used and pollutants and effluents associated with the production processes. For example, the emissions from the production process of the vulcanized shoes could have a tremendous negative impact on the air quality around the workshop if there were no treatments for these perilous emissions. The industry also

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poses environmental threats due to other issues such as energy consumption, intensive water use from the tanning processes, and improper chemical wastes treatment. Besides, the hazardous chemicals associated with the production process could definitely pollute the environment if the disposal of these chemicals was not treated properly. The hazardous chemicals are involved in the production processes for both tier 1 and tier 2 manufacturing units. In terms of tier 2 manufacturing units, Cao et al. [4] indicated that hazardous chemicals such as chromium salts are used in tanning production which converts the animal hides to the leather while the toxical substance, such as dioxins, is one of the most important by-products throughout the whole life cycle of producing PVC, a substitute of the leather material for the shoe manufacturing. These two materials are mostly used as components and materials for manufacturing in the footwear industry. When it comes to the shoe assembling processes (tier 1), Rajnarayan [43] showed us that organic solvents are frequently used in the assembly processes as the adhesive and glues, which are detrimental to workers’ heath due to neurotoxicity.

3.4.2

Transparency/Traceability Demands

According to Doorey [11], information disclosure could mitigate the social sustainability impact from the supply chain, address the forced labor issues, and improve labor practices. James and Montgomery [21] also identify the consumer demand for the sharing of information throughout the supply chain from fashion retailers. In the meantime, the apparel and footwear industry is foreseeing a trend to go beyond auditing, monitor beyond the first tier of suppliers, integrate sustainability to core business practices, and bring transparency to the supply chain [23]. As mentioned earlier, the Higg index has been created due to these increasing demands and trends. Several papers and researches also back up the trend and customer needs for information disclosure, highlighting the importance of creating a transparent and traceable supply chain [24]. Thus, the footwear brands and retailers should prioritize establishing a transparent and traceable supply chain when decision-makers are developing short- or long-term strategies.

3.4.3

Counterfeit Products and Quality

Counterfeit products did threaten the manufacturers and retailers of originator products [6]. Most of the footwear brands will allocate tremendous resources to address fake product issues each year. Apart from the counterfeit products, quality assurance is another challenge that most of the brands are facing. Although the product is manufactured in a standardized way, brands and retailers are still facing quality issues due to the decentralized and globalized supply chain. The quality issue of the products would not only lead to the return or recall of the product but also making the customer loose their confidence toward their purchase of the product.

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3.5 Supplier Relationship Management Given these issues and obstacles that the apparel companies are facing, most companies champion the importance of supplier relationship management. One of the most common ways is to build a healthy relationship between their business and global supply chain to drive incremental value identified in strategic sourcing projects. For example, some of the footwear companies have created a supplier relationship management (SRM) system to classify their suppliers into “Platinum,” “Gold,” “Silver,” and “On and Off” based on the performance and business value of these suppliers. Other companies have established a risk system to categorize the suppliers based on their risk in terms of sustainability and quality issues. The better the performance of the suppliers in either SRM or risk system, the more business will be rewarded to these suppliers. Although this seems a smart method to keep the suppliers in the fence of the code of conduct of the companies, there are several additional issues. For example, most of the footwear companies will need to monitor the performance in terms of sustainability and quality through auditing their suppliers on a frequent basis. These monitoring will increase the budget of these companies, given the resources such as workforce and frequent business travel needed. In addition, the opaque supply chain often prevents the auditing team from finding issues such as forced labor and child labor lurking inside the irresponsible suppliers.

4 Blockchain 4.1 What Is Blockchain You may hear about buzz words such as cryptocurrency, bitcoin, and litecoin even if you are not an investor of virtual currency. If you have heard these buzz words before, you may be familiar with “blockchain”—a technology behind all these virtual currencies. The idea of the blockchain architecture was first mentioned in Haber and Stornetta [15]. But this concept has been applied by Satoshi Nakamoto until 2008 in one of his paper titled “Bitcoin: A Peer-to-Peer Electronic Cash System.” [38]. This concept has been further developed and evolved to the blockchain technology that could be applied in more commercial and economic fields [16]. So, what is the blockchain? According to Drescher [12], blockchain is a digital ledger with blocks of information linked together. Each party on a blockchain has access to all the information, and no single person or entity controls a blockchain. Here is an easier way to explain this definition: The blockchain consists of a chain of blocks. Each block has two parts: header and body. Information such as the time stamp (time of the transaction) and hash (the identity of the block) will be calculated and stored in the header part while all the transaction information will be stored and in the body part. The hash is a

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function that converts your input (transaction information) into an encrypted output. The beauty of the blockchain is that all the transaction information (previous ones and the current ones) will be hashed altogether as a unique identity of the block— just like the fingerprint—and make any tiny change of data—even change in one block—impossible. Iansiti and Lakhani [19] identified the underlying architecture and characteristics of the blockchain: (1) distributed ledger or database, (2) accessibility within the network, (3) node to node communication, and (4) immutability. According to Drescher [12], each block of the chain structure has the following key characteristics: (1) immutable, (2) time-stamped, (3) append only, (4) secure, and (5) open and transparent. Blockchain technology could create a secure, transparent, authentic, and trustworthy supply chains due to its decentralized system and its features [1].

4.2 Key Terms (IOT/Ledger/Smart Contract/Proof of Work) Several key terms should be explained to understand the concept of the blockchain fully. These terms include (1) Internet of things (IoT), (2) digital ledger, (3) smart contract, and (4) proof of work (PoW). These terms are not only the fundamental building block of the blockchain but also are the reasons why this technology could create a secure, transparent, authentic, and trustworthy supply chains.

4.2.1

Internet of Things (IoT)

According to [40], IoT refers to the interconnection of smart devices (i.e., digital devices, computing machines) to collect data and facilitate the decision-making processes based on the data collected. Panarello et al. [40] further stated that the blockchain could address the security and privacy issues given the IoT are vulnerable to hacker attacks and data safety threats. In the context of the footwear supply chain, the IoT could connect all the digital devices and computers in the production facilities and collect the data out of this system. The introduction of the blockchain could secure the data is not hampered or hacked due to the characteristics and features of the blockchain. The decision-makers from the manufacturers and retailers could, therefore, trust the quality of the data and make the decision based on the data collected from the IoT system.

4.2.2

Digital Ledger

The essence of the blockchain is to record data or information collected by the IoT system digitally. The recorded information will then be encrypted in the blocks so that stakeholders could track the untampered information from the blocks. This is the reason why the blockchain is called the digital ledger.

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Smart Contracts

A smart contract is a computer program (functions and applications) having self-verifying, self-executing, and tamper-resistant properties [34]. According to Karamitsos et al. [22], the contract code will be uploaded and executed without the third parties into the blockchain network, and the blockchain network will assign each contract a unique address. In other words, the mechanism of smart contracts takes transaction—the information we want—as an input, executes the function, and transfers to the output of the events.

4.2.4

Proof of Work

Proof of work (PoW) is another important mechanism to secure the safety and security of the entire blockchain network. Although PoW was introduced by bitcoin to secure the safety of the transaction, this mechanism was used in the blockchain network, which assumes that each peer votes with his “computing power” by solving the proof of work instances and constructing the appropriate blocks [13]. Due to this consensus mechanism, not a single party in the blockchain network could tamper the information in the blocks.

4.3 Blockchain Frameworks and Services 4.3.1

Ethereum Versus Hyperledger Fabric

There are two most popular frameworks for developing and building the blockchain structure: (1) Ethereum and (2) Hyperledger Fabric. According to Prerna [42], Ethereum2 is designed upon smart contracts to be decentralized and is for mass consumption while Hyperledger3 leverages blockchain technology for business. Ethereum is a public blockchain network, while Hyperledger is more a private network for most of the business users due to the confidential information shared in the network. For footwear companies, they could develop their blockchain network by adopting both Ethereum and Hyperledger frameworks. The basic information of the suppliers (i.e., address and factory size) could be disclosed to the consumers through the public blockchain network. In the meantime, the confidential information such as the cost, sourcing price, and standard allowed minutes (SAM, etc.) should be delivered in the private application of the blockchain.

2 Ethereum

[Online]. Available: https://www.ethereum.org/. [Online]. Available: https://www.hyperledger.org/.

3 Hyperledger

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Services: Platform (AWS/IBM)

Although there are several platforms and services in terms of building the blockchain network, the authors highlighted two of them: Amazon Web Service (AWS) and IBM blockchain platform due to the needs of the most footwear brands and retailers. Both platforms are open-source platform and claimed that they could support the business to build scalable blockchain networks and ledger applications. One of the most significant differences between the two platforms is the application of AWS could be built upon both Hyperledger and Ethereum frameworks, while that of IBM could only be designed by using Hyperledger Fabric frameworks. In addition, there are other nuances between the two platforms. For example, AWS also provides AWS Blockchain Templates which could be used by the developers from the small business to build the blockchain architecture based on their own needs. The IBM platforms target most big corporates and also have created several business cases from the retailer giant’s globalized supply chain (i.e., Walmart blockchain). When it comes to the footwear industry, the decision-makers could select the right platforms based on their business needs and internal capabilities. For example, footwear companies like Nike Inc. could select AWS platforms for their small supplier, given the flexibility and the AWS Blockchain Templates provided. At the same time, Nike Inc. could customize the blockchain network for its closely cooperated big suppliers by using the IBM platform since the successful business case from the retailer giant’s globalized supply chain has been generalized.

5 The Benefits and Gains from Adoption To answer the first research question: What can the footwear companies gain from the adoption? This section focused on exploring the benefits and advantages that the blockchain technology could provide to the footwear supply chain and companies.

5.1 TOWS Matrix Based on current trends, characteristics of the footwear industry, and the power of the blockchain, a threats, opportunity, weakness, and strength (TOWS) matrix (see exhibit 1) was created to provide the reasons why companies should adopt the blockchain technology and what they can gain from the adoption. TOWS matrix is a tool by which strategies can be developed, and decisions can be made based on the identified strengths, weaknesses, opportunities, and threats [14]. As a variant of the strength, weakness, opportunity, and threats (SWOT) analysis, the TOWS matrix combines both internal factors (strengths and weaknesses) and external factors (opportunities and threats), making the decision process more comprehensive and thoroughgoing. Internal factors refer to both the strengths and weaknesses of the

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footwear companies and suppliers due to the unique features of the footwear industry and decentralized supply chain. External factors reflect the trends of the industry and the demands of the market. Four situations were created based on the combination of the internal and external factors: strengths and opportunities (SO), strengths and threats (ST), weaknesses and opportunities (WO), and weaknesses and threats (WT). The results derived from these situational analyses were condensed to answer the research question: What can the footwear companies and their supply chains gain from the adoption of blockchain technology?

5.2 Threats, Opportunity, Weakness, Strength 5.2.1

Opportunity

Opportunities refer to any external factors that companies and suppliers could tap into when it comes to the adoption of blockchain technology. Based on the literature review, the author identified below opportunities that are most relevant to the blockchain technology in the footwear industry: 1. Opportunity 1 (O1): The advent of digital technologies such as RFID and 3D designing and printing has shifted the traditional apparel and footwear supply chain to a digital era [7]. More and more digital devices will be introduced into manufacturing processes, which could generate tons of amount of data for decision-makers’ usage. All these data could be used as input for the entire blockchain network before being processed for the visualization from the stakeholders of the whole value chain. 2. Opportunity 2 (O2): By incorporating the Internet of things (IoT) and radiofrequency identification (RFID), blockchain is likely to affect critical objectives of supply chain management such as cost, quality, risk reduction, sustainability, and flexibility [26]. The combination of the IoT and RFID could strengthen the power of the blockchain and render it to address the issues mentioned earlier in terms of the sustainability, quality, and marketing strategy. 3. Opportunity 3 (O3): The apparel and footwear industry is foreseeing a trend of creating a transparent and traceable supply chain [24]. Such a trend could drive the change of the supply chain and push the industry to explore the innovative technology or methodology to render its supply chain more transparent and traceable. 5.2.2

Threats

Unlike opportunities, threats are the adversary conditions that companies or suppliers should overcome in terms of the adoption of the technology. Most of the treats could be risks due to external factors and market trends. This study identified the following

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threats and risks footwear companies and suppliers would be facing if they adopted blockchain technology: 1. Threat 1 (T1): Supply chain and reputational risks such as Rana Plaza collapse and forced labor issue could undermine companies’ reputations and public images [20]. Such scandals will cost not only the companies’ public representations but also corrupt the revenues and profits of the companies because of the potential boycotts from the customers. 2. Threat 2 (T2): The supply chain of the textile industry is highly decentralized and globalized [17]. This characteristic of globalization increases the risk of the suppliers being exposed to the different cultural and legal system and therefore increases the risk of violating the laws and regulations of the sourcing country. The decentralization of the supply chain also doubles the difficulties for the footwear retailers to monitor their suppliers and scramble to keep suppliers in the fence of companies’ code of conduct or sustainability commitments. 3. Threat 3 (T3): The viral message from social media has a huge impact on companies’ reputations and public images [49]. As mentioned earlier, the viral information from social media could impact target consumers’ purchase decisions even with trivial wrongdoings from one of the footwear companies’ suppliers. 5.2.3

Weaknesses

Weaknesses are the internal problems that most of the footwear companies and suppliers are facing. Normally, the inherent organizational structure and the characteristics of the industry could be the sources of these problems. According to the literature review, the authors identified the following weaknesses existed internally in the footwear industry: 1. Weakness 1 (W1): Apparel and footwear companies are facing substantial inventory issues due to quick response strategies [5]. Such problems lead to a tremendous amount of material waste generated annually [35]. Most of the waste ended up in the landfill and therefore have a huge impact on our ecosystem. 2. Weakness 2 (W2): Most footwear companies rely on outsourcing and subcontracting services of its production. There is a vendor relationship between apparel and footwear companies and their suppliers [17]. Companies such as Nike Inc. and Adidas AG do not even own one production facility through their entire value chain. This makes the companies have limited leverage over their entire supply chain and therefore lack the ability to monitor their whole supply chain. 3. Weakness 3 (W3): Most apparel and footwear companies require a shorter lead time than traditional manufacturing schedules [45]. This situation would increase issues such as long working hours and forced labor. 4. Weakness 4 (W4): Most of the apparel and footwear products are providing products at a low price to the market [17]. The lower price strategy makes these companies transfer their sourcing plan to lower-income countries and make the supply chain more decentralized.

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Strengths

Strengths are some areas in which companies have competitive edges. These competitive edges could differentiate the companies from their competitors in the marketing environment. In the competitive market, more competitive advantages the company has, more profits, and customer loyalty the company could be rewarded. The author identified three key strengths relevant to most footwear giants’ visions and values: 1. Strength 1 (S1): Most of the apparel and footwear companies have integrated sustainability into their business operations [46]. The integration could make these companies in line with conscious consumption demands based on the increasing market trends regarding sustainability. 2. Strength 2 (S2): Most apparel and footwear companies have a substantial economic and social impact due to their economic scale and great employment opportunities generated by the companies [17]. As mentioned in the previous part, three footwear giants hired more than 170,000 employees last year globally. 3. Strength 3 (S3): Most of the retailers and brands have committed to mitigating their environmental impact, such as reducing greenhouse gas emissions and recycling textile wastes.

5.3 Gains from the Adoption Based on internal and external factors listed in the previous part, this study analyzed four situations derived from the combination of these factors: strengths and opportunities (SO), strengths and threats (ST), weaknesses and opportunities (WO), and weaknesses and threats (WT). Under the scenario of SO and ST, the author figured out benefits by analyzing how footwear companies can use their strengths to take advantage of opportunities or avoid potential threats by adopting the blockchain technology. In terms of WO and WT, the author identified the gains by investigating how footwear companies can overcome weaknesses by tapping into the opportunities or avoiding external threats when applying blockchain technology throughout the entire supply chain. Next, the author listed all the benefits and gains from four perspectives: transparency and traceability, cost, speed (lead time), and mitigation of the social and environmental impact. The benefits and gains of the adoption could provide the fitting solution to the challenges that the footwear industry and supply chain are facing.

5.3.1

Transparency and Traceability

1. S1, S2, S3 and O2, O3: The characteristics of the immutability and chain structure could help to create a more transparent and traceable supply chain [26]. The potential of creating a transparent supply chain is in line with the customers’

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increasing demands of previous inaccessible information disclosure throughout the supply chain. This could also address the counterfeit product issues since all the products could be tracked down from the raw material to the final assembly attributed to this new technology. 2. S2, S3 and T1, T3: The transparent and traceable supply chain with supported data could provide a positive image of the company. Although most of the footwear companies have committed to mitigating social and environmental impact, few of them could deliver concrete results to respond to their commitments, especially when it comes to the issue existed throughout companies’ decentralized supply chain. After the adoption of the technology, the stakeholders and consumers would be able to quickly get access to previous inaccessible data (information) derived from the supply chain. These verified and hamper-resistant data could convince the stakeholders that companies were taking actions in fulfilling their commitments, and therefore, more investments and business opportunities would be rewarded. 5.3.2

Cost

1. W2 and T1, T2: Blockchain could build up a trusted relationship between suppliers(vendors) and fashion companies and audit-free business model, which reduces the cost of the audits in terms of the sustainability and quality issues of the products and the cost of the middleman (vendors) in the business [26]. As mentioned earlier, most footwear companies champion the importance of supplier relationship management (SRM) depending on the monitoring system of the performance of the suppliers in the quality, sustainability, and business spectrum. However, the maintenance of such an SRM system will increase tons of budgets of the company by using either the internal or external auditing team to catch up with the performance of the suppliers. The adoption of the blockchain would reduce such expense to a minimum or even zero if the old system being successfully replaced. 2. W2, W4 and O1, O2: The mechanism of blockchains such as automation, streamlined process, and processing speed could lessen the labor requirements and optimize the production process, which thereby reduces the production-related costs [18]. In the section of the introduction of the footwear industry, we mentioned the characteristics of labor intensive of the shoe production process, and several social and occupational health issues are associated with the manufacturing processes. Automated production processes could not only save the labor cost due to the reduction of the workers in the production facilities but also lessen the risks associated with the old-fashioned production processes. 5.3.3

Speed (Lead Time)

1. W1, W3 and O1: Blockchain could seamlessly capture data end-to-end through each digitalized production process [7]. These data could provide insights to

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optimize the production process and therefore reduce the lead time. For example, the exponentially increased amount of data could be fed into machine learning or optimization models and could improve the performance and accuracy of these models. The decision-makers could provide solutions to improve the working efficiency according to the hint from the outputs of the models. 5.3.4

Mitigation of the Social and Environmental Impact

1. S1 and T1: According to Kshetri [26], blockchain architecture could provide secure, trusted, and transparent data. These data could support the buying team of the footwear companies and brands to make responsible sourcing decisions and thereby refrain from social risks associated with the decentralized and globalized supply chain. The data and sourcing specialist could pick the right suppliers and reward the suppliers with more business opportunities based on the highquality and hamper-resistant data extracted from the blockchain network. Also, the business team could build up their simulation models based on historical data to evaluate the new suppliers and therefore shorten and facilitate the due diligence processes before working with the new supplier or sourcing in uncharted territories. 2. W1 and T2: Blockchain technology could mitigate production waste in a twofold way. First, the technology could track the data in each production process and identify the hot spots of material usage. Thus, the companies could focus on researching new solutions to tackle the hot spots identified by the technology. Second, the accessible data of the products could facilitate the recycling process due to the recognizable ingredients of the digital tag generated from the blockchain network. This could prevent tons of waste from the products from being landfilled and therefore encourage the usage of recyclable and eco-friendly materials.

6 Strategic Position in the Market In this section, we attempted to answer the last research question—Where can the blockchain position the fast fashion companies in the competitive market?—in two steps. First, the author tried to dig into the potential of this technology and identify if this technology is disruptive by using the definition of disruptive technology. Second, the author sought to figure out what competitive advantages could bring to the companies and how this technology could differentiate the companies from the competitors if they adopted blockchain technology by analyzing Roger’s diffusion of innovation theory.

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6.1 Disruptive Technology (Potential of the Blockchain) 6.1.1

Disruptive Technology Definition

According to Danneels [9], disruptive technologies would be those technologies that render established technologies obsolete and change the base of competition by developing the performance metrics along which firms compete. In other words, certain technology could change how the supply chain operates and replace traditional working methods with innovative ones. Also, the entire industry should change the methods on how to evaluate each participant’s performance in the industry. Kostoff et al. [25] also stated that disruptive technology could provide exponential improvements in the value of the process/products/services received by the customers. That is to say, disruptive technology could enhance customers’ experiences by its enormous improvements and added value to the services. In the context of the supply chain, we could expect the growth of the production efficiency and the development of the capability of the production processes. Kostoff et al. [25] further declared that disruptive technologies typically draw upon many diverse technologies and can be either a new combination of existing technologies or new technologies that cause major technology product paradigm shifts or create entirely new ones.

6.1.2

Why Blockchain Disruptive?

According to Azzi et al. [1], the blockchain network could replace the traditional and centralized enterprise resource planning (ERP) system with a blockchain-based and decentralized network. Unlike the ERP system, the specific architecture of the blockchain would totally change the way how the supply chain deals with their data extracted from the production process. Azzi et al. [1] also claimed that the unique chain structure and proof of work mechanism had lifted chain management to the next level, making the supply chain more transparent, authentic, and trustworthy. For decades, most of the retailers had been struggling to establish and traceable and transparent supply chain and scrambling to collect the data that could reflect real situations throughout their complete supply chains. These are fragments of evidence that blockchain is a disruptive technology that renders established or traditional technologies obsolete. Besides, Hughes et al. [18] mentioned most of the companies should redesign their business models and organizational structures so that they could benefit from the adoption of blockchain technology. That is to say, blockchain could flip over the supply chain ecosystem and therefore change all the evaluation methods throughout the supply chain, which proved this technology is disruptive ones as it could turn the base of competition by improving the performance metrics. Apart from these two features, blockchain could also affect key supply chains management objectives such as cost, quality, speed, dependability, risk reduction, sustainability, and flexibility [26]. Thus, blockchain is a disruptive technology because this technology

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does provide exponential improvements in the value of the process/products/services received by the customers based on Kshetri’s argument. Finally, this technology evolves from diversified technologies. By incorporating technologies such as RFID, proof of work, smart contracts, and cloud-based solutions, the technology could meet the key supply chain management objectives mentioned above [26]. This feature demonstrated that technology is a disruptive one, as blockchain is the combination of existing technologies and new technologies. These features and traits of blockchain technology extracted from the literature review perfectly satisfy the definition of disruptive technology.

6.1.3

What Disruptiveness Means to Footwear Companies?

Companies could gain from the adoption of this disruptive technology from three perspectives. First, the adoption of this disruptive technology could address the challenges and issues companies are facing, such as inventory issues, perplexing supply chain risks, and social and environmental concerns. As mentioned earlier, the blockchain network could provide high-quality and immutable data extracted from the production processes and facilities throughout the footwear supply chain. The decision-makers could refer to these previously inaccessible data and, in turn, to make the decisions that could address these long-existing issues in the industry. Besides, the adoption of this disruptive technology could support footwear companies to establish the competitive edges in response to the new blockchain era given the blockchain technology could rewrite the rule of the competitive market. The early adopters could create their standards and evaluation methodology of the supply chain and became the standards makers and leaders in this uncharted territory. Finally, the adoption could build a long-term competitive advantage by reducing the risk and saving the cost in the long run, given the benefits the technology could bring to the supply chain and disruptive features of the blockchain technology.

6.2 Diffusion Theories In this section, the author investigated Roger’s diffusion of innovations and the growth model of emerging technology to identify the position of the companies in the competitive market if adopting blockchain technology. The author also referred to the analysis of blockchain from Hughes et al. [18], Azzi et al. [1], and Kshetri [26] to figure out what the potential for the development of this technology is and what competitive edges this technology could bring to the companies.

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Rogers’ Diffusion of Innovations Theory

Rogers [44] classified the adopters based on the innovativeness, including innovators, early adopters, early majority, late majority, and laggards. The differences among these adopters are associated with the timing of the adoption of the new technology and the acceptance level of embracing the latest technology. Based on Rogers’ theory, only one-sixth of the adopters have been categorized into innovators and early adopters. Rogers [44] also claimed that the innovators and early adopters are more likely to hold leadership in the social system. Since the application of the blockchain in the apparel and footwear world is in its “fledgling stage,” the footwear pioneers could be regarded as innovators or early adopters if they started adopting technology at this point. The leadership position gained from the early adoption of the technology could bring these companies the competitive edges in the market if the trend of the transparent and traceable supply chain was inevitable. The first practice of the adoption could establish the novel standards, innovative working methods, and new evaluation metrics of the performance for the supply chain, which would make the majority competitors in the market to follow the leaders in the latter stage of the implementation of this technology in the industry.

6.2.2

Growth Model

The growth model theory could support the argument that technology could bring a leadership position to the companies if they adopted the technology at this point. According to Porter et al. [41], there are four phases for technology growth and development: (1) emerging, (2) rapid growth, (3) maturity, and (4) decline. Once the technology emerged, there is a period of rapid growth, followed by an inflection point and slower growth as the product enters a period of maturity. Like the organic entity, the technology will be declining after it reached the maturity period. Thus, before reaching the inflection point, the technology still has enormous potential for the development in the period of rapid growth. Based on Hughes et al. [18], Azzi et al. [1], and Kshetri [26], blockchain is still in the phase of rapid growth but not yet hit the inflection point. For example, several case studies indicated most of the companies in other industries are still piloting the blockchain projects in their supply chains. The technology is still a fresh concept for the footwear industry. Besides, several challenges and barriers need to be addressed before blockchain technology can be fully adopted in the supply chain ecosystem. Thus, there is considerable potential for developing this technology at this moment. The pioneers of the adoption could enjoy the bonus dividend due to the exponential development of the technology used in the context of the supply chain.

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6.3 Position of the Company Based on the theories abovementioned, the disruptive blockchain could make footwear companies become the innovators and early adopters at this moment. Such roles in the competitive market could bring the leadership position to these pioneer companies and make them gain competitive edges before this technology hits the inflection point. These competing advantages could render these companies to establish the novel standards, innovative working methods, and new evaluation metrics of the performance for the supply chain and distinguish them from the competitors in the footwear industry.

7 Application Area and Cases Analysis 7.1 Application Area Based on the literature review, blockchain has a variety of application areas in the industrial, financial, and commercial world. This section would focus on the application area related to the supply chain due to the scope of this paper. According to Hughes et al. [18] and Tian [48], blockchain could be applied in the transportation and logistics management, inventory management, supplier management, raw material or ingredients identification, and transaction/payment in the supply chain. These areas are highly relevant to the businesses of the footwear supply chain. The blockchain technology has already been used frequently in some areas, while it is still in the theoretical stage for other areas. For example, the payment system for the transaction has been developed due to the popularity of the virtual cryptocurrencies. This practice could be extended to all the transactions that happened throughout the supply chain. In addition, IBM Food Trust—a data-sharing platform/network among all the participants in the food industry—has created a successful case about inventory management and identification of the hot spots for food waste by implementing the blockchain technology. However, applications, such as raw material or ingredients identification, are still in the pilot phases as there are several hurdles that companies need to overcome (i.e., equipment replacement, workforce training, etc.).

7.2 Cases Analysis We identified three cases that are related to the supply chain of retailing companies. Also, we noted that functions realized in these cases could also address the issues and problems that the footwear companies are facing mentioned earlier.

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Alibaba

Chinese online retail giant Alibaba collaborated with AusPost, Blackmores, and PwC to investigate the application of blockchain to fight against food fraud [27] As mentioned earlier, most of the footwear companies have committed to recycling the wastes generated from their products or production processes. However, inaccurate material information creates obstacles for the recycling processes, and most of the waste ended up in the landfill instead of being recycled as promised by these companies. This case shows a successful example to address the issue by tracking the raw material for the footwear products and therefore overcome the challenges from the recycling process. This case also shows the potential of addressing another counterfeits issue in the footwear industry since the consumers could track the information of the supply chain and prevent from buying fake footwear products.

7.2.2

Walmart

Walmart has worked with IBM to track food safety by incorporating the blockchain technology. The company also used the technology in authenticating not only the package but also the customers and couriers in its logistics sector [26]. The solution used in the logistics area created an excellent example of how to track every production step from the production of the components to the finished products manufacturing and the shipping information from the component manufacturing mills to the assembly production facilities. This practice could prevent social risks such as undeclare outsourcing, which refers to the products that are produced in the facilities without permission from the footwear retailers and brands. Most undeclared facilities have high risks of social sustainability issues such as child labor, forced labor, unannounced outsourcing, and occupational health and safety issues. The footwear companies are normally struggling in tracking their supplier outsourcing their orders to some sweatshops or even prisons under the current suppliers’ monitoring system. This solution could solve this issue and therefore mitigate the social impact accordingly.

7.3 Everledger Everledger, a London-based start-up, uses the blockchain-based solutions to verify the origin of products [26]. The system could refrain from the certification process for the diamond products. Currently, most of the footwear companies require their suppliers to certify their factories or accept the audits from external organizations due to the quality and sustainability concerns. However, most suppliers are paying

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tons of money to get such certifications or being audited by third parties, while the footwear brands are reluctant to increase the sourcing prices due to the competitive production market. The cost could undermine the profit of the suppliers and, in turn, exploit the workers’ wages to cover the loss from the certifications and audits. This “Everledger” case is an excellent example to showcase the possibility of creating a certificate-free and audit-free for the footwear supply chain. In the meantime, the footwear brands could still monitor their suppliers’ performance in terms of quality and sustainability because of the implementation of the new technology.

8 Barriers and Potentials 8.1 Barriers Although there is a promising future of blockchain being adopted in the footwear supply chain, the early adopters still need to face the barriers and challenges from politics, social, economic, and technical perspectives. We identified the following barriers in this research: • Complexity of laws, regulations, jurisdictions, and institutions across a global supply chain [26]. The blockchain technology may not be able to get access to every corner of the supply chain given different countries may have distinct laws and regulations in terms of the implementation of the blockchain technology. • Collaboration among all relevant parties [26]. As mentioned earlier, the footwear brands have limited leverage over most of the small suppliers due to the business quantity. Thus, the footwear companies should figure out how to convince the suppliers to embrace the new technology and disclose all the data from the production processes. • Implementation of technology-based solutions for suppliers, both in developed and developing countries [26]. The full implementation of the blockchain technology will need to integrate other technology and digital devices and services. However, this will be the obstacle of the suppliers in underdeveloped countries where the suppliers could not easily get access to these digital devices and services. • High cost for incorporating cloud service and RFID technologies to make the blockchain technology work in the supply chain; and [18]. • Lack of knowledge concerning blockchain at the workplace of the supply chain. In this case, more blockchain technicians or specialists should be involved during the adoption processes.

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8.2 Potentials These challenges are just like a double-edged sword. The solutions behind these challenges could push the development of this blockchain technology to the next level. For example, the collaboration between tech companies and apparel and footwear companies (i.e., Vechain and H&M collaboration) could lessen the technical barriers of the adoption. The technical breakthrough could prompt more companies’ adoption and thereby reduce the cost due to the economic scale. More successful use cases and adopters could also push the policy-makers to redesign the policies to facilitate the development of this technology. Thus, there exists a tremendous potential for the adoption of the technology, though the barriers and challenges mentioned above.

9 Conclusion In conclusion, the authors recommended the footwear companies to adopt the blockchain technology throughout their supply chain at this moment since the benefits and competitive advantages could bring to these pioneers if they adopted the technology. To answer the first sub-research question, the authors fed the TOWS matrix with the inputs extracted from characteristics of the footwear supply chain and the challenges that the footwear industry is facing. The authors then obtained the output by synthesizing and analyzing based on the literature reviews. According to the analysis of the results from the TOWS matrix, we highlighted what benefits the footwear companies and their supply chains can get from the adoption of the technology. The results were investigated from four perspectives: (1) transparency and traceability, (2) save the cost (eliminating middleman/vendor/verification), (3) speed (lead time), and (4) mitigation of the social and environmental impact. In addition, the authors analyzed where the blockchain will position the company if the implementation of the technology is in the supply chain by reviewing the definitions and characteristics of the disruptive technology and Roger’s diffusion of innovations theories. The author concluded that disruptive blockchain could make footwear companies become the innovators and early adopters at this moment. Such roles in the competitive market could bring a leadership position to these companies and make them gain competitive edges before this technology hits the inflection point. Several cases were displayed to prove the potentials and possibilities of this technology could bring to the supply chain of the footwear companies and the possibilities of addressing the issues that have been troubling the industry for decades. Finally, the author mentioned that early adopters would face the barriers and challenges from politics, social, economic, and technical perspectives. But these challenges are just like a double-edged sword. The solutions behind these challenges could push the development of this blockchain technology to the next level. Thus, the technology still holds for promise though the implementation of the technology has several barriers and challenges.

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Appendix Exhibit 1: TOWS analysis

Opportunity: O1: The advent of digital technologies, such as RFID and 3D designing, and printing has shifted the traditional supply chain to a digital era. [7] O2: By incorporating the Internet of things (IoT) and radio-frequency identification (RFID), blockchain is likely to affect key supply chain management objectives such as cost, quality, risk reduction, sustainability, and flexibility [26]. O3: The apparel and footwear industry is foreseeing a trend of creating a transparent and traceable supply chain [24]

Strengths: S1: Most fast fashion companies have a huge economic and social impact due to their economic scale and high employment opportunities generated by the companies [17]. S2: Most of the apparel and footwear companies have integrated sustainability into their business strategies [46]. S3: Most of the apparel and footwear companies have committed to mitigate their environmental impact by reducing greenhouse gas emissions and recycling textile wastes

Weaknesses: W1: Apparel and footwear companies are facing substantial inventory issues due to quick response strategies [5] Such problems lead to a tremendous amount of waste generated annually [35]. W2: Most apparel and footwear companies rely on outsourcing and subcontracting services of its production. There is a vendor relationship between these companies and their suppliers [17]. W3: Apparel and footwear companies require shorter lead time than traditional manufacturing schedule [45]. W4: Apparel and footwear products are providing low price to the market [17]

S1, S2, S3 and O2, O3: The characteristics of the immutability and chain structure make the supply chain more transparent and traceable [26]

W1, W3 and O1: Blockchain could seamlessly capture data end-to-end through each digitalized production process [7]. These data insights could be used to optimize the production process and therefore reduce the lead time. W2, W4 and O1, O2: The mechanism of blockchains such as automation, streamlined process, and processing speed could lessen the labor requirements and optimize the production process, which thereby reduces the production-related costs [18]

(continued)

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(continued) Threats: T1: Supply chain and reputational risks such as Rana Plaza collapse and forced labor issue could undermine companies’ reputations and public images [20]. T2: The supply chain of the apparel and footwear industry is highly decentralized and globalized [17]. T3: The viral message from social media has huge impact on companies’ reputations [49]

S2, S3 and T1, T3: The transparent and traceable supply chain with supported data could provide a positive image of the company S1 and T1: According to Hawlitschek et al. [16], blockchain architecture could provide secured, trusted, and transparent data. These data could support the buying team of the companies to make responsible sourcing decisions

W2 and T1, T2: Blockchain could build up a trusted relationship between suppliers(vendors) and retailers and audit-free business model, which reduces the cost of the audits in terms of the sustainability and quality issues of the products and the cost of the middleman (vendors) in the business [16] W1 and T2: The blockchain technology could mitigate product waste from two perspectives. First, the technology could save the materials and reduce wastes during the production process. Second, the traceable data of the products could facilitate the recycling process due to the identifiable ingredients of the digital tag generated from blockchain technology

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Designer Activism Strategies for Sustainable Leather Product Designs V. Nithyaprakash, S. Niveathitha, and V. Shanmugapriya

Abstract In this chapter, we discuss the leather product usage in ancient times and contemporary age, the properties of leather and the trends of the leather processing. Later, the environmental impact of leather processing is elaborated along with the breakdown of the assessment tools. To sustain the leather demand and face the challenges posed by it, the agenda proposed by the research conglomerates and affiliated authorities, designer activism strategies for promoting recyclability of leather and measures to advocate second life for virgin leather products, alternative leather material initiatives and new technology options were investigated through case study analysis. This investigation identifies the possible affirmations concerning the direct role of designer activism in promoting sustainable leather product designs. This study concludes circular design options for leather processing using vegetable tanning methods and promotes the use of biodegradable leather material alternatives. Keywords Sustainability · Design · Leather · Leather alternatives · Environment · Recyclability

1 Introduction Leather is one of the materials that has been used continuously ever since Iron Age. Leather product usage could be traced to the ancient time periods. The reason that makes leather as one of the most sought-after materials is attributed to its makerfriendly properties. Leather’s preferred material characteristics from the perspective of users and product designers range from being malleable and flexible to being tear V. Nithyaprakash (B) · S. Niveathitha · V. Shanmugapriya Department of Fashion Technology, Bannari Amman Institute of Technology, Coimbatore, India e-mail: [email protected] S. Niveathitha e-mail: [email protected] V. Shanmugapriya e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. S. Muthu (ed.), Leather and Footwear Sustainability, Textile Science and Clothing Technology, https://doi.org/10.1007/978-981-15-6296-9_4

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resistant. Leather’s compatibility with mechanical surface treatments and chemical treatments makes it a versatile substance for large-scale industrial manufacturing. It is processed from the originally biodegradable skins of slaughtered animals using chemicals, and in the process it is converted into an inorganic material that slows down the rate of degradation as well as the amount of degradation. Along the conversion process of leather, toxic substances are left over in the effluents whose impact on the environment remains a global challenge to be combated. As leather is highly valued and treated with esteem respect by consumers, to sustain its stature and demand a multipronged approach and environment-friendly processing strategies are required in the current scenario.

2 Leather Product Usage in History and Contemporary Age 2.1 Leather Product Usage in History The oldest leather product usage recorded in history is almost 5500 years old and identified as a shoe [1]. It was discovered in an American cave by the archaeologists. In fact, the shoe also bears enormous similarities with the make and style of contemporary European shoe [1]. This speaks volumes about the leather design characteristics and its semiotic attributes evolved since then. The earliest usage of leather in Iron Age corresponds to skin garments traced to the peat bogs of Jutland (200 BC–500 AD) [2]. Leather in garments could be traced to as old as ninth century (Bible AD 845). Leather clothing was preferred for its warmth. Hence, it was heavy, less flexible and difficult to wash [3]. Capes of Denmark indicate the presence of skilled craftspeople who made these leather garments [4]. Leather dress variants in the form of hoods and cloak were discovered in one of the cemeteries at Harford [5]. Leather over garments like caftans and coats was lined with fur and sheepskin [6]. Meanwhile, leather’s use in foundation garments such as bikinis is also identified among the female athletes of ancient Rome [7]. Archaeological evidence of bikinis indicates the date to be as old as first century AD [8]. Further evidences of leather foundation garments were traced to the mosaic Villa Romana del Casale in Italy where more elaborate applications such as breast bands, briefs, acrobats and other entertainers were identified [7]. Archaeological evidence of gloves made of fur was identified in medieval graves of Unterhaching near Munich, Germany [9]. In another such excavation in the Saint-Denis Basilica, leather belt with silk embroidery and silver buckles was identified [10].

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2.2 Leather Product Usage in Modern Era and Contemporary Age Technology revolution and research developments in science during the early phases of modern era helped to diversify the leather process [11]. The shiny black colour shoe leather, patent leather, was invented in 1819 as a result of one such development [12]. Prior to the mechanization of tanning in the 1860s, leather usage was traced to products like costume and clothing, working equipment bags, military tools, household objects, bookbinding, toys, saddles, shoes and boots [11]. Industrialization of leather processing in the late nineteenth century [13] and decentralization of fashion in the early twentieth century expanded the usage of leather in many products as far as highly personalized leather gifts, niche shoes, interior upholsteries, automotive accessories and iconic leather handbags. First, leather product among French leather goods to be accorded luxury status is a wallet made from a single piece of leather without any stitches, which earned itself the name “Sans Couture” [14] in 1898. This leather wallet later fetched a silver medal at the universal exhibition in 1900 for its innovative features [14]. The newly ordained leather’s luxury status paved the way for its increased preference in highly personalized accessories. By the 1930s, many leather accessories for both men and women gathered momentum as it witnessed the discovery of new evening bag styles including the clutch bag [15]. 1955 marked the issue of beautiful crafted leather gifts and presentables [16]. Soon leather occupied a central stage in the global luxury fashion value stream. At the moment, leather material usage could be traced to extended fashionable leather products like Chanel’s patchwork stockings [17] and Kanye West’s joggers [18], designer automotive interiors, designer upholsteries, computer accessory covers, stationary wraps and prosthetics. Thus, the material options for leather products have expanded like never before and helped evolve the leather material perceptions even more. Product life cycles in fashion have shortened, and consumers are motivated to purchase new items every season. The fast-changing fashion cycles are encouraged through planned and aesthetic obsolesce [19]. In these circumstances, they do not form any personal relationship with them [20]. Further fashion creates symbolic boundaries between what is fashion and what is not fashion [21]. The designers take credit for infusing these symbolic values in fashion goods. All the agents involved in creation and promotion of fashion area are susceptible to cultural innovations, changes in lifestyle, values and attitude [22]. According to McCracken, fashion values newness contrary to patina that acts as a visual proof of kind of status. In postmodern world, consumers are driven by new tastes and preferences [23]. Fashion is not without fetishism; leather corsets, lingerie and catsuit are among the common clothing fetishes [24]. The emergence of the Italian leather further enhanced the appeal of luxury leather products drawing from its ethnic fine traditional craft [25]. By 2004, leather could be identified in almost every category of fashion starting from haute couture to fast fashion at all price points [24]. Just like other fashion goods, leather also experiences trend cycles.

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Apart from fulfilling the performance attributes by virtue of its mechanical properties, the symbolic values surrounding the leather material and its craft also evolved along with the progressive applications. In fact, leather has become a synonym for fine craft, aesthetics and classic quality, especially among the fashion accessories. It further escalated the value propositions of leather products never mind even if it happened to be a staple utility product or an exclusive high-end luxury fashion product. In the current scenario as per the European Union source, 13% of finished leather is used for automotive industries, 17% of finished leather is used for upholsteries, 19% of finished leather is used for handbags, 8% is used for apparel making, 41% is used for footwear and 2% is used for glove making [26]. The global luxury leather goods market research report for 2020–2026 considers leather a luxury good meant to be extravagant and treasured [27]. A classic example for being most treasured material in USA is shell cordovan, and a name of rich Burgundy or dark rose raw material consumed in making exclusive leather shoe has been the ubiquitous choice for US Presidents from Ronald Reagan to George W Bush [28]. The leather product market is expected to engross worth US $629.65 billion by 2025 [29] that projects a requirement of 430 million cows annually by 2025 to make handbags, belts and shoes.

3 Leather Properties 3.1 Leather Properties from the Perspective of Product Design Characteristics The desired leather characteristics streamline two aspects, namely 1. mechanical and physical properties, and elasticity and fracture toughness and 2. tactile property of softness [30]. The mechanical properties are assessed by quantifying the modulus of the material; however, the tactile property of leather stems from psycho-epistemic logic of the cultural prototypes constructed since the ancient period instead of engineering property. The ability of leather to deflect during handle or stretch under tensile force actions and recover to its original shape constitutes a supreme characteristic property [31]. It is suitable for a whole lot of traditional leather craft techniques like stamping, embossing, carving, etching, embroidery and engraving. Each traditional technique imparts unique aesthetic effects on the leather in such a way that the legacy surrounds the place of craft and the end product made using that technique. One such classic example of the legendary craft is Moroccan leather embroidered Berber bags. The iconic artisan embellished leather bag comes with different patterns. The quality and finish of the artisan-made leather bags bear significance not only to its fine soft malleable material nature but also to the craftsmanship practices survived until today [32]. In fact, both fine craft and Moroccan leather’s superior quality endowed the name “maroquinerie” for fine leather goods.

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In fact, from the perspective of product design characteristics, the leather is finished accordingly, to meet the end product functions and desired design attributes. Leather possesses the flexibility to be finished both on its grain side and on its flesh side [33]. Leather is capable of coloured, split, conditioned, polished and paintable appropriate to the end use requirements. Hence, leather comes in various types, namely: full-grain leather—where the skin is presented as such replete with animal’s scars and stains, corrected grain—leather surface sanded for uniformity, hotstuffed—conditioned with grease, split leather—where the skin is sliced into thinner layers for use in gloves and garments and suede—split leather sanded on both sides [34]. Leather can be tanned and finished to be any of the following types [35]: i. patent leather—the hide is finished and lacquered to give a glossy shiny surface, ii. glaze—the leather is finished to provide a hard polished surface, iii. natural grain surface—the leather is finished to retain its natural grain and iv. embossed—the leather surface is pressed with a picturesque art on its surface [35].

3.2 Leather Properties by Source Types In the global leather product platform, cattle, cow, goat and sheep form the major livestock species from which the raw material leather is extracted [33]. Leather from cow is generally addressed as hides, and leather from goat, sheep and pigs is classified as skins. Cow leather, the most common type of leather, is renowned for its strength, stiffness and durability. According to an estimate, 66% of the leather products are made from cow leather [36]. It is this stiffness and strength which render it suitable for pyrography processes of varying temperatures. Cowhide is processed and finished to yield different surface effects such as patent leather, embossed leather and split leather. Nine percentage of the leather products are made from goat and sheep leathers [37]. Unlike the cow leather, goat leather is more soft and supple, an intrinsic leather property that it is allegiance to the presence of lanolin in it [37]. Goatskin leather is water resistant contributing to easy wash care maintenance. Sheepskins and goatskins finished on grain side are used in soft leather products like handbags. Meanwhile, the goatskin finished on the flesh side yields velvet like nap with good tear strength and tongue strength, thus making it a preferred choice for exclusive fashion garments. Moreover, sheepskin is compatible with several types of leather treatments like sanding, suede, grain correction, full-grain treatment, hot-stuffed and split. Fur skin is a general name given to products made from the skins of animal species like rabbits, wildcats, deer, fox, etc [33]. They are used in caps, hats, gloves and garments. Suede leather surface is brushed to produce a soft velvet-like texture [35] considered a luxury in fashion owing to its soft pliable drape. Unlike the other surface-treated leather types, suede effect is produced from cowhides, pigskins, goatskins and sheepskins.

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4 Leather Processing Trends Leather is one among the three majorly used material groups along with fur and skin ever since prehistoric period [38] for its product design characteristic properties and maker-friendly engineering properties. But it is not a readily available material from nature. It is obtained from the animal skins which are subjected to highly toxic treatments in order to convert the skin into a most sought-after and maker-friendly raw material. Animal skin peeled from the slaughtered animal’s carcass needs immediate treatment to prevent it from decay. The process of converting the skin into a flexible and malleable material is referred as tanning. Processes such as salting also aid in persevering it temporarily. This temporarily preserved leather offers the potential to be processed either as parchment, oil- or fat-cured leather, tanned leather or fur [39]. If the hair on the skin is retained and processed to hold strongly on the skin, then it is converted into a fur material. For the other three products, parchment, tanned leather and oil-cured leather, the skin needs a lime treatment for removing the unstructured proteins present on the flesh side of the skin [40]. The processed skin thus yielded is categorized as pelt. Further, the pelt could be used for manufacturing parchment or transparent leather for drum linings [41]. For producing tanned leather, the pelts are treated with tanning agents [41]. Tanning methods range from vegetable tanning, oil tanning and chrome tanning. The pelts are treated with oil at warm temperatures to facilitate oxidation, which in turn produce a soft form of leather referred to chamois leather [42]. The pelts treated by vegetable tanning or chrome tanning produce a more versatile substrate with improved stability and properties. The leather substrate thus produced by vegetable tanning and chrome tanning is compatible with subsequent processes such as splitting, dyeing and finishing [41]. Texture imparting finishes are applied only at the last step when the leather maintains a dry state. In other words, leather has been allocated for a product and performing of leather has begun. The surface of the tanned leather is treated with pigments and dyes to yield desirable surface characteristics that enhance the aesthetic appearance of the leather substrate [43]. Industrial tanning process constitutes 85–90% of the leather quantity produced across the globe [44]. Industrial tanning uses chromium VI which is classified as toxic cancer causing allergen. The remaining 10–15% of global leather produced employs oak bark tanning and vegetable tanning [45]. Leather tanned with oak bark yields a softer variant of the leather suitable for producing white clothing [46]. For producing leather gloves, the tanned leather is treated with alum oil and other materials as combination or formalin [46]. In oak bark tanning, the tanned hides are allowed to be hanged on ropes in open sheds for several days and involve processes such as paring or shaving to level thickness, colouring and treatment with oils and greases to produce attractive surface finishes [47]. Grain surface is treated with waxes, proteins such as blood and egg albumins to produce attractive surface finishes. This method originated in San Segundo, Avila, Spain [47]. Tanning process know-how was passed to the subsequent generations orally until seventeenth century. Aftermath, King Louis

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XIV of France initiated documentation of scientific process of leather tanning [47]. Late nineteenth century marked the demand for many kinds of heavier duty leather catering to the evolving mechanization of industries [48]. For example, belting leather for driving machines, leather for textile looms, saddler leather, harness leather and shoes ushered the requirement for flexible and large volume tanning methods [48]. Vegetable-tanned leather suffered from irregular properties and uneven characteristics [48]. This necessitated faster and large-scale tanning methods like chromium tanning to produce sturdier industrial leather products. The newly evolved largescale tanning comprised an expanded set of operations like beam house operations, tanning, post-tanning, dyeing and finishing [48]. Beam house operations further incorporated several stages of processing like soaking, liming, fleshing and splitting to clean the skin, remove the adipose tissue, remove hair and adapt the leather thickness to a desired value [47]. Tanning includes deliming, bating and pickling. The objective of tanning is to partially degrade the skin structure to facilitate penetration and subsequent fixing of chemicals, adjust pH and stabilize the structure of collagen by adding tanning agents. Industrialized tanning uses inorganic products or minerals consisting of chromium salts, aluminium, iron, titanium, etc [47]. On the contrary, vegetable tanning only used natural vegetable extracts but required more time. Organic compounds like quinines, aldehydes, sulphochlorinated paraffin and multiple resins are also used for tanning [49]. Another alternative method of tanning is enzyme tanning which is less pollutive compared to the chrome tanning. Potential alternative evolved subsequent to the abolishment of chrome salts and leather formaldehydes appears to be active cross-linking (ACL) agents, as it claims the finished leather to be toxic free [50]. This is attributed to the ability of ACL to crosslink the functional groups and chemically stabilize the fibrous protein collagen in leather structure without leaving behind traces of chrome in the finished product [50]. Once leather has been tanned, post-tanning processes involve: shaving, neutralization, retanning, drying, fat liquoring, summying and drying. Dyes and surface treatments are added to lend itself suitable for current fashion trends [35]. Dyeing refers to group of operations generically represented as colouration. From chemistry perspective, dyes are classified as natural and synthetic dyes. In the earlier days, leather was dyed with plants with naturally occurring materials that includes indigo, saffron, green span or verdigris [51]. Today, 70% of the leather is dyed with plastic dyes and aniline dyes [52]. In order to guarantee the dyeing quality, dyestuff parameters such as fastness, penetration power, matching capability, degree of opacity and method of use are held accountable. So, the desired synthetic dyes are acid dyes, direct dyes, basic dyes, metal complex dyes and reactive dyes [53]. Pigments form an alternative method of colouration. Contrary to dyes, these substances are insoluble and applied in aqueous or organic dispersion [54]. Unlike the dyes where the dye molecule is absorbed into the morphological structure of leather, the pigments are deposited in the surface pores and hold on them. Hence, pigments cover the leather surface defects. Finishing comprises the various surface treatments meted out on the leather to yield final surface texture, character and appearance. Process like trimming and ironing helps to remove the peg marks and holes [55]. Buffing with emery paper

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produces more even leather but leaves behind lot of dust, so dedusting with air blasts improves the leather life by removing the impurities [56]. Buffing and embossing were the two mechanical treatments applied in finishing [57]. Wet finishing techniques such as spraying, padding and roller coating are used [57]. Glazable finishes, protein binders, thermoplastic finishes and nitrocellulose finishes are preferred surface coating techniques to achieve new homogenous surface textures. Furthermore, depending on the amount of pigment contained in the finish, more classifications came into practice [58]. Types of such finishes are full aniline finish; completely transparent without any type of pigment, semi-aniline finish; finish with certain covering power by moderately adding pigment and dyestuffs, pigmented finish; and greater covering effect by adding high quantities of covering pigments [58].

4.1 Impact of Leather Processing According to UNIDO report, out of 1000 kg of rawhides processed only 250–300 kg of leather is produced and leaves behind 600 kg of solid waste [59]. Moreover, in this conventional transformation process from hides to final leather, 452 kg of chemical substances are added to 1000 kg of wet salted hides and around 380 kg of the added chemicals go as part of waste [60]. Chrome used in tanning ends up as carcinogenic compounds (chromium VI) in finished articles, thus posing health hazards for the end user. Leather processing inflicts disastrous twin effects on both human health and environment. And the industrial waste produced by leather during its processing is classified under Class 1—solid waste, highly toxic [61]. The environmental impact of the leather processing and the consequent transport is measured via life cycle assessment tool that indexes a numerical value calculated by assessing the hazardous impact on the environment produced per unit conversion of raw materials as per the stated process. It is presented as Higg Index. The Higg Index of conventionally processed leather (chrome tanning method) hovers around a value of 161 [62], whereas the alternative synthetic leather produces a Higg Index of 59, almost just above one-third of the conventional method [62]. Faux leather and faux suede are the synthetic alternatives to animal hides and skins. Faux leather and suede can be used on almost all products made of natural leather [35], but the inherent difference in property is they are non-porous and very hot compared to the natural leather. But large numbers of colours are possible with synthetic alternatives. However, the synthetic alternatives have a polyurethane film coating which again has its own share of toxic load on the environment. On the contrary, Pete Lankford design director for Earth Keepers and Timberland Boot in 2011 claimed “A pair of leather boots that last twice as long as a synthetic alternative, will end up with half the environmental impact in the long run” [63]. The leather processing industries initiating sustainable measures also co-asserts the strategic decision-making functions pertaining to the business process of leather products, thus covering all and sundry

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players as a whole in the leather product trade. Hence, life cycle assessment encompasses and multiplies the effects of sustainable measures, a deterrent for reducing the toxic load of leather processing industries.

4.2 Breakdown of the Assessment Methodologies The necessity to weigh the toxic impact generated at each stage and regulate the process stream gathered momentum when studies identified chromium (VI) as carcinogenic relevant to nose and nasal sinus infections [64]. Thus, imperatives, perspectives and rationales fostering sustainability measure emphasis on how to apportion and account for the industrial wastes generated at every phase of leather process stream got initiated [65]. Subsequent developments in the sustainable front lead by the Leather Working Group established protocols to monitor the environmental impact caused by leather processing [66]. Life cycle analysis provides a factual analysis of products during its entire life cycle in terms of sustainability. It assesses the environmental impacts of product or services from cradle to grave. The life cycle of leather comprises four major stages: 1. hide processing stage alias tanning stage, 2. leather material conversion stage, 3. product distribution and retailing stage and 4. post-consumer stage [67]. Meanwhile, the waste generated at the product distribution and retailing stage comprising returned goods, unsold goods and seized counterfeit goods is more clean and valuable [67]. Life cycle assessment as per ISO 14044 comprises four main phases, namely goal and scope, inventory analysis, impact assessment and interpretation. Goal and scope defines the product and its life cycle in addition to the description of system boundaries [68]. The guidelines for ISO 14044 were framed with reference to the elemental definitions coined in ISO DIN 14067 for quantifying the carbon footprints at each stage of processing [69]. Inventory analysis observes all environmental inputs and outputs associated with product or service by monitoring the raw materials used, energy consumed, volume of pollutants emitted to the atmosphere and quantity of effluent streams let out [68], whereas the impact assessment phase classifies the environmental impacts, evaluates on terms of what is important or essential to the leather manufacturing firm and translates them to environmental themes. A classic example among them is effects of global warming on human health laid down by the analysis and recommendations of UNIDO 2012 report [70]. The chosen theme is presented as an element of corporate social responsibility drawing reference to the audience they cater to. In the last phase, interpretation, ISO 14044 standards describe a number of checks to test whether conclusions are adequately supported by data and procedures complied by the corporate organization [68]. There is direct correlation between increase in anthropogenic greenhouse gases (methane CH4 ), nitrogen oxide (N2 O) and carbon dioxide (CO2 ) and increase in global average temperature. Leather industry activities use hazardous chemical substances that generate a major portion of CO2 with a direct impact on global warming [70]. Leather processing activities have a direct impact on

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global warming through CO2 emissions [71]. Currently, there is no universal methodology or a general accepted agreement on calculating the environmental impact of leather processing. Best available techniques (BAT) reference document for tanning of hides and skins provides valuable insights into leather processing [72]. Impact categories are scientific definitions that link the specific substances to specific environmental issues. The major impact categories identified so far as severely affecting the environment and used in leather processing impact assessment are 1. global warming potential (GWP), 2. acidification potential (AP), 3. photochemical ozone creation potential (POCP), 4. ozone layer depletion potential (ODP) and 5. eutrophication potential (EP) [72]. Global warming potential measures the impact of greenhouses on the environment [73], whereas acidification potential assesses the intensity and amount of acid gases released into atmosphere that culminates in acid rain [74]. Meanwhile, photochemical ozone creation potential quantifies the amount of change inflicted on the ozone layer due to gas emissions and the direct degradation of ozone layer is monitored via ozone layer depletion potential [71]. According to epa.gov, CO2 has a GWP of 1 regardless of time period used as reference. Its concentration on earth will last for thousands of years [75]. As per the Romanian tanning industry case study, finishing phase generates highest pollution in terms of CO2 followed by dying phase and beam house phase for processing a full-grain assortment of bovine leather that is chrome tanned [76]. The technological process reference materials and resources considered for life cycle assessment of full-grain bovine leather assortment include bovine wet salted hides, bovine pets, wet blue and crust weighed in kilogram unit and the equivalent quantity of natural gas in kilogram units consumed for water and air heating [77]. Electricity in kilowatt hour consumed by tanning machines, Process water quantity in kilogram units, Chemical substances equivalent quantity in kilogram units, waste for recovered from technological process in kilogram units and the waste water resulting from leather processing in kilogram units [77].

5 Strategies for Producing Environment-Friendly Leather Leather as a brand is highly valued and respected by its consumers all over the world irrespective of the environmental impact it leaves behind [78]. In order to maintain and carry forward its value from the perspective of well-made sustainable piece of leather, all the value chain partners in the leather product network should work together in eliminating the toxic hazards produced as a result of leather processing [78]. Given the hazardous nature of leather wastes generated during the life cycle of leather goods processing and its iconic status, an inclusive design approach as well as a flexible process which could promote better relationships with the environment and the consumer demand forms the need of the hour [79, 80]. So, green peace treaties and eco-friendly awareness have etched sustainability requirement as mandatory for every leather product design, thus making it an essential design ingredient. This

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inculcates a need for engineering sustainable design constituents. Rather in other words, sustainability shall be an inbuilt function for each of the materials and methods used in converting the design concept into product henceforth. In order to express the luxury fashion’s solidarity to sustainable initiatives, the Paris Ethical Fashion Show was organized in 2004 that comprised 20 fashion designers. Later, this effort garnered support and mobilized popularity that went to grew up to 90 designers by 2009 [81]. At the same time, the fashion consumer moved towards individual expression and sought new ways of expressing their identification in the city life [82]. This new found consumer tastes were pioneered by Gen Y consumers who embarked on living their passion over acquiring status symbols [83]. Again nonindulgence in impersonating others provided the impetus to nurture value-driven fashion solutions [84]. The novelty for twenty-first-century customers is defined in terms of personalized products and services [85]. In 2018, the world’s leading business event on sustainability in fashion with 1300 international key players was organized [86]. French fashion, the largest shareholder of luxury fashion segment, pronounced its intentions to become the most sustainable fashion capital by 2024 [87]. These efforts have also roped in global organizations like “Leather Working Group” (LWG) to ensure and promote sustainable practices of leather-processing industries [88]. The crucial stage necessitates major design interventions. Further, it creates a scope for rethinking the entire value chain cycle across a new plane. The value chain partners include brands, designers, craftsmen, testing societies and standardization institutes, new technologies, rawhide suppliers, alternative materials, new process routes, tanners, research institutes and technologies for recycling. Among all the progressive efforts taken up by different partners of the value chain, the role of designer is crucial to the promotion of sustainable or circular leather product design stemming from the fact that the motives of the fashion system in terms of sustainable fashion demand and social agenda of fashion revolve around the creative work of the product designer [23]. Several scholars like Manzini, Margolin, Papanek [89, 90] and Thackara [91] do agree social innovations and design as a catalyser for creating visions of possible futures. The role of research institutions also assumes importance as advent of research tools like EDFR futuristic techniques add enterprise to identify and forecast future demands of design [92]. From the sustainable leather product design perspective, the designer’s role could range from not only creating a fashionable product, but also his responsibility to use the resource for a longer span of time in the design’s life cycle, the ability to reuse waste materials in the design development and predict the scalability of the designs. In overall, the direct role of designer in producing a sustainable leather design encompasses activities right from i. the development of new conceptual framework of design, ii. advocating reuse of waste and second life product strategies, iii. developing key performance indicators for ensuring sustainable practices along the material supply chain, iv. engaging craftsmen, customers and entrepreneurs in co-creation, v. developing new material alternatives and vi. adopting environment-friendly new technologies and process routes.

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5.1 Development of New Conceptual Framework for Design and Key Performance Indicators for Ensuring Sustainable Practices FAMEST, acronym for the project footwear, advanced materials, equipment and software technologies, aims to produce new concepts of fashion, technical, personalized and customized work shoes of high added value [93]. These high-value additions along with the sustainable design needs are incorporated by deploying suitable material development plans, production process and post-consumption processes [94]. This is crucial as 41% of the leather produce is consumed by footwear products [26]. The entire life cycle of the product is monitored through flexible and agile technologies with the sole objective of developing solutions to reuse the waste generated in production and post-consumption [95]. This project is supported by a consortium of twenty-three companies spread across the whole value chain of footwear which includes makers and distributors of leather material, insole and sole components, chemical substances, software firms, equipment and logistic firms [94]. Thus, multidisciplinary and complementary competencies are entitled through selective choice of the tools used in the footwear manufacturing, futuristic design concepts, new chemical substances, new material options, new functionality components, Tech 4.0 advanced production methods and marketing technologies for 4.0 [94]. The project scope draws from the belief, and true environmental sustainable footwear products begin with creation process that is design [96]. It is at the design stage that the entire footwear value chain and the environmental aspects from selection of raw materials to the end of product life can be envisaged. So, the following sets of design strategies are floated to reduce environmental impact and develop ecological footwear products [94]. The project embarks on a set of ten guidelines, namely “i. improved efficiency of the material used for the product making, ii. improved energy efficiency of the processes through reduction in the number of production process steps engaged or in other words the lesser the number of production processes greater the energy efficiency, iii. design for cleaner production thus less harm to mother earth and atmosphere, iv. design for durability, v. design to optimize functionality to facilitate multiple product functions, functional optimization and product modularity, vi. design to reuse and recycle demonstrating the capability of easy disassembly of the product and simplification of materials for easy recycling, vii. avoid potentially hazardous substances and materials, viii. design to reduce the environmental impact in the use phase, ix. employ environmentally more efficient distribution channels to deal with the objective of less packaging waste, lesser packaging requirements and eliminate unnecessary packaging and x. optimize the end of product life opportunities through reduction of product complexity, easy separate marking of material for channelizing their recyclability and facilitate communication regarding end of product life opportunities to the consumer” [94]. The NYU stern centre for sustainable business in partnership with council of fashion designers of America developed the kerning standard for leather goods and shoe manufacturers. These KPIs are defined with reference to a set of nine

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topics framed within CFDA guide for sustainable strategies [97]. These metrics can be broadly classified into i. manufacturing process metrics that includes materials, process, design philosophies and other energy resources used in the manufacturing, ii. supply chain metrics for monitoring raw material suppliers, distribution service providers and other logistic service providers and iii. community and social responsibility metrics for managing people-related matters and business strategies. The community and social responsibility metrics represent the first KPI that focuses on establishing pay structure, measuring employee satisfaction, improving minority representation and committing to X% of women workers [97]. Supply chain metrics advocates local purchase policy in case of raw materials advocates stringent audit procedures to ensure the logistic supply chain partners strongly abides by ESG guidelines [97]. Manufacturing process metrics encompasses all the activities right from design development to packaging. It adopts the design philosophy “design for sustainability” with the objective of creating zero waste patterns for cutting, manufacturing waste reusage and recyclability of product at its end of first life [97]. The design scope is defined on the lines identifying circular opportunities for materials used up in the manufacturing. Further, it also pledges to reduce the usage of HVAC equipment and adopt the policy of reducing energy consumption every year [97]. It enforces optimized sustainable process methods with emphasis on reducing environment impact caused by them. Thus, the Kering Standard for sustainable leather goods and shoe manufacturers encompasses all and sundry means by which a designer could pursue active strategies along the design stream, sourcing stream, production stream, sales and distribution stream, machinery and energy stream, material stream and by-product stream. The affordability of the KPI’s deployment lies in the fact that either any combination of them or as a whole or as an individual metric is incorporated by the designers or brands parse or entrepreneurs alike.

5.2 Advocating Reuse of Waste and Second Life Product Strategies Recycling of the products alone is inadequate to question or change the attitude of fashion buyer, given the semiotic value of leather as a luxury product. For true change, design should focus on sustainable lifestyles instead of mere sustainable products [98]. Therefore, a broader understanding of design is required especially while advocating second life product strategies. The challenge lies in reaching critical mass of designers and consumers to be powerful enough to start change on a large scale [22]. For a more sustainable production system, the general relationship between product, producer and end user should shift towards slower cycles, more local production and much more valued product–person relationship [99]. An exceptional example of resold value being greater than its original retail value could be traced among

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celebrity-owned Birkin handbags and Kelly handbags [100]. Further, Brundtland’s definition of sustainability states the all-encompassing responsibility to fulfil the needs of the society without depleting or reducing the environment’s resources. In other words, strategical relook at the market share of the traditional virgin materials used, obtaining materials from sources declared as waste and their scalability for expansive end uses of the contemporary world, needs assertive measures.

5.2.1

Scope of Recycling Concept

The challenge lies in finding appropriate markets for leather recycled products [67]. From the perspective of product value and economic viability, recycled leather product is classified into three categories, i. downcycled leather product, ii. recycled leather product and iii. upcycled leather product. Downcycling refers to the failure to recover leather’s original value, and hence, the recycled materials shall end up as feedstocks or supplements for alternate processes such as agricultural engineering [101]. Recycling leather refers to reconstituted leather recovered from leather wastes whose value relies on its purity based on which they are classified into low range (90% purity) [67]. Upcycling refers to the processes that are applied to extract the embedded chemical compounds from the leather waste [67]. At hide processing stage, anywhere around 70% by wet weight of the hides might go into waste streams [101]. Microbial fermentation of solid wastes helps to recover the waste fluid streams and is reused for pertaining applications. Chemical processing of trimmings and split pieces generated during the conversion stage produces films and adhesives [102]. Soares discovered a new approach to life cycle analysis of footwear products by advocating reintroduction of clean solid waste generated during production by re-engineering the process from design to product modelling [103]. But still each category of recycled leather product requires separate technology and enterprise framework to realize its product value.

5.2.2

Reuse of Wastes Generated in Manufacturing Process

Wastes generated during second stage of leather life cycle such as fabric trimmings and leather cut pieces are assembled into square patterns of 25 cm3 and later rectangles of 50 cm3 in the course of converting the clean waste into a high heel boot [104]. However, the polygon pattern shape and size are determined from the volumetric area of the target upcycled product to be manufactured via a mathematical method [104]. DNP acronym Design na Pele is a project initiated at a children shoe-producing factory situated at Rio Grande do Sul, Brazil. This company produces around 15 thousand shoes per day. The project aims to reuse the solid waste materials generated in the production phase, and code names the process as reverse logistics [105]. As usual, the design development starts with traditional factoring of trends and seasons. Along the design development process, the volume of leather waste in the form of

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smaller pieces is also studied upon as a factor. So, the design development team is also vested with the task of building a unique model that shall consume the leather scraps generated in the production floor which is otherwise discarded as landfills. The more the amount of small wastes generated in the process goes as waste, the higher gets the end product price. Thus, reuse of small leather scraps and large leather scraps produced during manufacturing begins to be planned right from the footwear design development and specification stage itself [105]. In this new approach, the designers are informed about the nature of the waste generated in the process and the amount available. Using these inputs, a new conceptual shoe design is developed determining which waste type, colour and quantity in what proportions are deployed. However, the varnish type, opaqueness and texture are factored according to the design type and ultimately, no single leather product produced by this method has the same character and texture [105]. Every product is unique by way of the composition and colour usage. After the approval of the model, the waste scraps are reintroduced into the production process. The larger waste scraps and the smaller waste scraps are used separately. The smaller leather scraps are used for decorative articles such as petals of a flower or strips of ribbons, and the disadvantage is that it consumes more time and cost. The waste savings in the form of reusage accounted for 15% reduction in solid waste disposal, approximately 21 kg of leather waste [105]. It belongs to the category of green product design that aims to build completely from recycled materials. In this cradle-to-cradle life cycle planning process design for disassembly, choose only decomposable materials that are rapidly renewable—bamboo, cotton, natural rubber, cork, etc., are emphasized [106].

5.2.3

Reusability of Design Information for Leather Goods

Design information pertains to all and sundry involved in design process starting from design brief, design details, design process, design methodology and leather productmaking process [107]. Design process starts with understanding the product attributes by analysing the design brief or looking forward to solve a design problem. The design requirements are understood through brainstorming the brief and identifying the key design elements. Design research process is about being artistic and open ended. Thus, the whole design process is guided by the inspirational references unlike the scientific research process where the objectives are framed to solve the defined problem or to take you closer to the problem. Perceived design details of the leather products are those availed from the leather products offered on sale, forecast reports and consumer preferences. Design details per se comprise the whole picture beginning with the conceptual part explaining the manner in which the design elements are presented along the design construct and its supposed purport. Further, the product-making phase incorporates all the design details with the help of craft and technology on the material leather. The material per se encompasses all the constituent parts of the product structure. Meanwhile, the visual composition of the leather product design is constructed by employing the elements and principles of design upon the material in a conceptual framework. It is

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the conceptual framework that defines the attributes of the design as per the trend. So, an unsold leather product in the sales and distribution stream might require design reconciliation in order to render it marketable as per the new designed value propositions and product concept. Design reconciliation may start anywhere from reorganization of visual design composition by shredding the product components and refabricating the whole design to just rearrangement of visual appearance through reorganization of visual hierarchy. Achieving new visual hierarchy through minor tasks like surface treatments will be the effective process route in terms of time consumed and cost involved, whereas refabricating of design concept shall entail higher expenses. Technology, skill and energy, all these are incurred during the redesigning process. Kate Fletcher’s project “local wisdom” took an inventive step in proposing that sustainability can emerge from a wealth of simple interactions with people. The interactions were recorded as a story shared by the people which in turn opened up insights relevant to the people’s reflections on the experience about the product [108]. By any means, these interactions might not fit the objectives of commercial opportunities but rather open up a new front especially for discussing the everyday practice of product usage. In fact, it indirectly reflects on the culture each and every person has pursued diligently. Just as in the local wisdom project where reflective practices of dress culture provided the means to frame cultural understanding of the clothing as critical to garment’s sustainability [108], it is essential to frame cultural understanding of the leather products to determine the reuse of design information. Drawing from the initial findings of “local wisdom project”, a questionnaire was developed to comprehend the cultural understandings of leather product usage among the southern metropolitan cities of India. And it was circulated among 500 leather product customers who are identified as regular users of leather products. 1. Which age group you belong to? A. 17–21, B. 22–26, C. 27–31, D. 31–40 yrs. 2. Do you have the habit of carrying a leather article or wearing a leather jacket? YES/NO 3. If yes, how often you don a leather jacket or any leather carried accessory such as handbag or pouch in a week? A. Twice a week, B. No matter how many times a week leather article is an indispensable part of my outerwear. C. Only when I do outdoor travelling. D. Only once or twice. 4. What sort of bonding does the leather product give you like _____________? A. I wish to carry a leather article or don a leather jacket as it gives me a status symbol. B. Leather product adds on to the overall outlook and elegance. C. For etiquette reasons to fit on to the occasion. D. A leather product gives me a personal attachment and makes me feel intuitively more accessible.

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5. During leather product selection and purchase are you interested in _____________. A. Avant-garde design concept of the product, its presentation. B. Brand values, legendary leather design details. C. Design, leather raw material sources and its claim of how delicately it was made using artisans (craft). D. Only physical appearance of the product; latest look, celebrity endorsed product, latest fashion, etc. 6. Would you prefer to appreciate innovations in leather product silhouettes wrought by recycled and re-engineered materials? YES/NO 7. If your mother/father owned a leather product of genuine leather and good quality, would like to _____________. A. Refurbish (renovate and add value) with new style features and functions (change the visceral quality and consequently behavioural experience also). B. Retain its renowned traditional form and original design concept by giving preservative treatments and mending (retain the visceral quality and more emotional). C. Give preservative treatments and convert it into modern silhouette appropriate for today’s usage as its original design has the potential for getting repopularizing (change the visceral quality and behavioural quality—defining new behaviour). D. Though its original design did not have the potential for repolarization (coming back into fashion), yet would like to convert into suitable product and reuse due to its very good quality and value of leather (change visceral quality, change behaviour but appreciate the value of leather). Forty percentage of the surveyed respondents belonged to the age group of 17– 21 years old. And in every age category, there were nearly about 20% of the respondents. Among the responses to leather product usage in a week, 84.5% accounted for leather product usage as an indispensable part of outerwear. This conveys a mass preference for leather product usage. With leather scoring high on being considered an important and essential life style product underscores the significance of its cultural value. However, the emotional bonding with leather products reflecting on their cultural understanding could be confirmed from the subsequent response where only 54% of the respondents indicated that leather products give them a personal attachment and make them feel more accessible. Later, 67% of the respondents supported brand values and legendary leather design values. And almost 68% of the respondents preferred refurbishing the leather product with new style features and functions. The preference for refurbishing undermines the possibility of reusing the material in two different ways, 1. adding new value additions on existing design details and 2. extending the cultural value with modified functions and design details. By either way, design information is reused but with necessary changes. Hence, cost components, technical know-how and technology all are incurred in the redesigning phase. Actually, it is reused by redesign.

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5.3 Co-design Co-design aims at interlinking the designers, craftsmen, customers and entrepreneurs to create leather products of unique value by accommodating the environmental, cultural and social principles of sustainability. In the co-design framework, the working supply chain partners are classified into two categories, i. stake holders and ii. duty holders. The supply chain partners who align with the demand positions or the pull positions are grouped as stakeholders, and the supply chain partners those who take the role of fulfilling the demand and satisfying the customers are deemed duty holders [109]. This discussion on co-design shall feature the brand initiatives and activism strategies undertaken by the designers. Tuscany a word eponymous for genuine leather design still pioneers in the production of vegetable tanned leather product [109]. Every year, “Craft the Leather International workshop” brings budding designers to observe and learn the value of leather material through interaction with leather craftsmen of Tuscany. It is a perceived endeavour to package “artisanality” approach in producing innovative leather goods, the cultural component in sustainability [109]. At Hidesign in India, the leather design requirements are transferred to the product by understanding and gaining insight about the vegetable tanned leather properties, detailing, product aesthetics and conceptualizing for whom they are producing for [110]. Through this interaction between designers and craftsmen, the fashion trends are communicated to the craftsmen so that they can enhance the design and in turn the designers learn from the craftsmen how they translate the design requirements and aesthetics in the product. Similarly, eco-craft also evolved through the interaction with the craftsmen of Jaipur who produced handmade sandals. Jaipur craftsmen were spurred on by the great Mahatma Gandhi’s Swadeshi Movement emphasizing make your own chappals and cloth as a symbol of independence [111]. And India’s growth in leather exports is attributed to the strong link between traditional craftsmanship and innovations the designers are able to bring in [112]. In another case, the art of making fish leather old to several centuries and indispensable part of Nordic culture was revived. The difference between fish leather and other biological leather materials in the case of brand “Mayu” identifies with the zero waste process methodology followed by skilled Indian craftsmen and upcycled leather produced from fish skin a by-product of food supply chain [113]. Stella of Stella Soomlais is a pioneer in manufacturing handbags in a sustainable and innovative way. The design strategies are developed to minimize waste such that the cutting leftover materials are converted into small accessories like purse, wrist band and key chains with the help of expert craftsmen. The brand’s innovative cutting pattern management plans the second life product patterns on the perimeters of the first life product patterns in order to close the loop [114]. Overall flat design methodology is followed with emphasis on functionality and efficacy. Rather in other words, this strategy provides an interaction design platform for both designers and craftsmen to co-create leather designs. Around 2.4% wastage has been reported one

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of the lowest across the industry as of now, but they further endeavour to bring the waste down to zero percentage [114]. In the perspective of Luna Mazzolini, leather is a by-product of food industry; if not processed into a useful material, it becomes just waste threatening to pollute the world. Her design ideology revolves around goal of using only hand stitching techniques and screwable fasteners in making the leather product [115]. So that, the entire product can be dismantled and reconverted into another product after the end of the life of the original product [115]. Innovative double-row hand stitching was applied which added on to the flexibility of disassembling the layers. Thus, handmade craft was once again used do the fore in redesigning the end of life leather products. Other discarded scrap materials were recycled into bonded leather which ended up as linings for new product development [115]. She also promoted the use of bio-based polyurethane coatings to extend lifespan of leather products further. The choice of bio-based polyurethane not only eliminated the fossil fuel petroleum sources but also provided better durability and water resistance. This coating exhibited the property of ageing gracefully upon exposure to sunlight. The treated areas shone brighter and brighter upon prolonged exposure to light [115].

5.4 Developing New Material Alternatives 5.4.1

Biofacturing

As the name suggests the product, a garment or an accessory is synthesized with the help of bacteria from sugary tea solution, a unit-level stage directly. It bypasses all the intermittent stages of material development. The merging of biological organisms and human-made manufacture will cause a radical shift as we seek to grow products, rather than manufacture them, from cells or mycelium. In other words, grow made products. The fermentation between the bacteria and sugary tea solution leaves behind a sheet layer-like substance on the top which is taken out once it is 2 cm thick and washed in cold soapy water. The thick layer-like substance, when dry, is suitable for cutting and conventional sewing. This new innovative method of production is being pioneered by Designer Suzanne Lee and seen as a cradle-tocradle approach with no waste and direct synthesis from the raw material in a span of few days. Luxury brand Gucci is pioneering a new eco-friendly and sustainable alternative. This material is already 20% of Gucci’s ready to wear collection, and about 40% RTW collections use this material [116]. Another example is microbe fermented fashion where the bacterium Acetobacter is used to convert wine into vinegar resulting in a by-product, a skinny rubbery soft skin-like substance. This substance is scaled up into a garment form without any seam requirement. As the material produced by the action of a bacterial culture on the alcohol is cellulose, it is naturally degradable in the environment. In another variant of biofacturing, manipulated grown structures and products were directly produced [117]. Designer David Benjamin identified two different types

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of genetically modified bacteria. He mixed them in a large Petri dish with nutrients and cultivated their growth [118]. Along its growing phase, the bacteria were allowed to interact with compatible fungal structures. Thus by growth, flat sheets of material with distinct rigid and flexible regions were formed [118]. It produced a natural pattern texture and was lightweight. It was used as envelopes in boats, airbuses and buildings. In one other pavilion architecture, a pavilion geometry was created using an algorithm that aligns a continuous silk filament across the scaffold [119]. These scaffolds were fed with groups of silkworms which filled the gaps between the scaffold frames. An outcome of digital and biological fabrication was pioneered by MIT media laboratory [119]. Similarly, young tree branches of willow oak tree were pruned and allowed to grow on the former frames. At intermittent nodal locations, the tree branches were grafted along with the former so that it grows into a single solid piece [120]. Once the graft reaches the required shape through continuous growth, it is harvested as table or chair determined by the base former shape. In a similar initiative, Designer Jen Keane grew rhaeticus bacteria on interwoven yarn membranes in the shape of shoe mould [121]. The bacteria grow around the bamboo yarn and form a impregnated surface.

5.4.2

New Vegan Leather Alternatives

The first ever vegan fashion week was held at Los Angeles in 2019. It was a conscious effort to cut down on fur and exotic leather trade besides exploring the technologies and manufacturing means for producing and branding leather alternatives. Parallelly, sustainable fashion weeks were also held along the similar lines emphasizing the virtues real, sustainability and recyclability alike. Continuous efforts paid off with the finds like coffee, grass leather, pineapple leather, mushroom leather, fungi leather, coffee leather, crop waste leather, apple leather hogging the limelight of fashion shows. One such pioneering effort was by Sebastian Thies, a sixth-generation shoemaker who helped his brand to creating sneakers from real, sustainable, recycled and fully vegan materials. Another such brand initiative saw Humour.noir a luxury brand succeeding in producing and marketing animal-free, sustainable and exclusive accessories [122]. The brand prides itself on its handbags especially which are handcrafted by Italian craftsman using natural vegan materials like pineapple leaf-based leather, Cartina: a composite of recycled paper and cork. Another value addition to the handbag is its 24-carat gold-plated accessories that is free from both lead and nickel. On top of all these innovative measures is a bio-leather alternative, a product conceived and developed by modern meadows. Modern meadows advocate biofabrication process, where animal-free, recombinant collagen is produced by means of DNA editing tools that assist to engineer special collagen-producing yeast cells [123]. The DNA editing tool-assisted yeast cells produce collagen equivalent to that of cow’s leather. The biotechnology kit further organizes the collagen to recapitulate it into fully grown biological collagen structure characteristic of that identified in an animal hide. Later, this collagen is forwarded to tanneries to undergo the remaining process in leather production. This technique of producing bio-leather draws from

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inspiration from 3D bioprinting technique adopted by Organovo that makes skin models of liver and kidney organs. This bio-fabricated material is also available in liquid form that provides endless opportunities to spray or pour and moulded into a 3D form without any joining operations such as sewing [124]. This material is commercially sold in the name of “Zoa”. Zoa can be produced in any required density, thus capable of being moulded and shaped; besides, it is also compatible with other materials in forming composites [125]. Further, it can also take many textures. In 2017, Zoa graphic shirt was launched by modern meadows which is now partnering with world class luxury brands for new product developments [126]. Meanwhile, brands like Bolt Threads identified the prospects of growing leather directly from mushroom mycelium which even capitalized with the support rendered by renowned fashion designers like Stella McCartney. This work gained momentum when British furniture maker Sebastian Cox collaborated with Designer Ninela Ivanova to investigate mushroom mycelium’s potential in growing contemporary furniture out of moulded wooden strips [127]. At the beginning of the process, the mushroom that feeds and grows upon the base of wood or corn or straw, etc., is wetted. Once it is damp, the substance is put into a bag and allowed to pasteurize. Pasteurization kills bad bacteria and propels the growing phase. Then, the mushroom colonies are allowed to develop which usually takes around two weeks of time. Later, the grown up substrate is broken and compressed into desired shape and size. Desired dye colours are added to finish the leather alternative. It is commercially known as Mylo. Actually, the base used for growing mushroom is a post-consumer waste comprising anything from corn cobs, wood chips, straw, etc [128]. Brand ZVNDER that makes mushroom leather fashion accessories has also collaborated with Nat-2 to make vegan shoes out of mushroom leather and recycled plastic water bottles [128]. Mylo is a breakthrough material that looks, feels and behaves like handcrafted leather [30]. Carrying forward the trend, the brand Vegea introduced leather alternative made from by-products of wine industry that had expanded horizons of usage ranging from fashion to automotive and transportation industries. Brands like nuuwaï, Poétique Paris and Happy Genie initiated the usage of apple fibre leather in fashion accessory designs. Apple fibre leather was made from leftover apple wastes. Frumat is a leather alternative prepared from 50% leftover apple waste and 50% polyurethane [129]. It is available in variety textures and surface treatments such as laser printing and embossing that can be afforded on its surface. Even more environment-friendly material was developed by Tree Tribe and Elpis Studio by soaking, drying fallen teak tree leaves and pressing them into sheets. These sheets are capable of being mended with cotton to yield soft interior structures [130]. Another leather alternative from fruits is pineapple leather that is made from composite mixture of pineapple harvest waste, PLA and petroleum-based resins [131]. PLA is linear aliphatic thermoplastic polyester made from plant-based matter. PLA is made by extracting the starch from plants and converting it into a fermentable sugar, such as glucose, by enzymatic hydrolysis. Fermentation of the plant sugars produces lactic acid. When water is removed, a cyclic intermediate dimer—lactide—is produced [132]. The pineapple fibres are extracted through decortication process which are washed, dried

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and degummed later. These degummed fibre produce cotton like flexibility of virtue of which it is converted into a felt like sheets. These sheets are later converted into leather alternative through a subsequent process along with resins [132]. The Pinatex leather alternative is composed of is currently composed of 80% pineapple leaf fibre (PALF) and 20% polylactic acid (PLA) fibres and is 100% biodegradable [30n]; 85–90% of the Pinatex leather alternative is biodegradable except the remaining 10–15% that forms the coating material which is not biodegradable. The dyes are used for colouring the Pinatex material as per the GOTS standard. The resins used on them are compliant with the standards of the Apparel and Footwear International RSL Management (AFIRM), an organization that serves to advance the global management of restricted substances [133, 134]. It was developed by a leather industry consultant Carmen Hijosa. Pinatex now works with 43 high-end labels and brands that include players like Hugo Boss and H&M [30]. Between the efforts of the designers and these leather alternatives to see through their successful transition into product forms lies the compatibility of their mechanical properties vis-a-vis viscoelastic properties. A vegan leather alternative that transcended these requirements is Desserto a cactus-based leather alternative produced from nopal cactus leaves [135]. Other forms of vegetal leather include the one produced by coating cloth with raw rubber and then smoking it to make a durable, waterproof material. This technology had been used for years by rubber tappers to make waterproof bags out of old sugar sacks [136]. The products made from vegetal leather feature mainly assorted bags and purses, cosmetic cases, cool briefcases, duffel-style travel bag, etc. Luxury brand Givenchy has introduced an eco-friendly vegetal leather velvet belt [137]. This piece features a wide-to-narrow style for a balanced play on functionality and femininity to achieve a high-fashion look. Among all the bio-leather alternatives, these three materials, Zoa, Mylo and Pinatex, are seen as potential leather alternatives and commercially feasible for bulk production. All the three materials Zoa, Mylo and Pinatex seek to eliminate the most environmentally impactful phase of leather, the rearing and slaughter of livestock for its raw material [30]. While Mylo and Zoa are able to eliminate the industrial chromium tanning process by choosing natural tanning methods, Pinatex does not require this stage as it is finished with alternate materials [30]. All the three materials require comparatively shorter periods of growth. Mycelium mushroom the raw material for Mylo grows in a matter of weeks [138], and Pinatex raw material “pineapple” requires eighteen to nineteen months for harvest [132]. In case of Zoa for developing collagen from yeast, it takes around two weeks [127]. In fact, these material properties are far better than PU-coated artificial leather which require a minimum of two weeks’ time for their production [132]. Conceptually, the possibility of creating a finished material equivalent to natural leather from the hides in terms of composition and structure has been evolved [30]. They offer the scope of incurring less waste material; rather in other words, the material can be grown to required specification. These materials can be handled by artisans and industrial technology alike.

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Natural Textile Composite Alternatives

Designer Tamara Orjola developed a composite from pine needles and bioplastic binders. It produced high-quality look accompanied by a fibrous feel [139]. Technically, it was durable, hard and tough capable of fulfilling functions like load bearing, insulation, decorative and styling functions [117]. It was 100% biodegradable. Normally millions of pine needles go to waste. The pine needles were crushed and soaked. Later, the soaked material was steamed and carded. Subsequent to carding, binding and pressing operations were carried out to finish the material [139]. It was found suitable for applications such as carpet, paper and furniture. Designer Tjeerd Veenhoven developed palm leather from areca palm tree leaves and wood [140]. The dry leaves and brittle leaves of the areca palm tree were dipped in a biological softening solution and processed into substrates [117]. It offered resistance to tear; at the same time, it was flexible and strong, it provided a natural leather like feel and it was also capable of fulfilling functions like protection, decoration, comfort and identity. It held immense potential to be used as a replacement for leather, plastic and rubber materials [140]. Footwear and upholsteries started experimenting with palm leather for new product developments. A manufacturing firm Sedacor JPSCORK Group based out of Portugal developed a smooth, soft and warm material from cork [141]. The cork was steamed and boiled to impart elasticity to it. Later, the substrate was cut into thin sheets. These sheets were capable of performing functions like protection, comfort and decoration; hence, it found itself used in applications such as apparels, upholsteries and footwear [117]. Technically, it was durable, water resistant and stain resistant. Studio Sarmite based out of Latvia developed pine skins from the bark of the pine trees [117]. The pine tree bark was peeled as soon as the tree was cut and blended with natural ingredients and processed into flexible tenacious substrates [142], and it was soft, resistant to water and tear. Because of its tensile properties, it ended up in construction of apparel products. Another firm Dekodur GmbH & Co of Germany produced bark cloth [143]. The bark cloth is a substrate made from a composition of fig tree bark, high-tech phenol and amino plate papers [117]. It offered UV protection and found to be resistant to scratch, water and heat. Hence, it was preferred for furniture, wall panels, indoor coverings and ceiling panels. The fig tree bark was hammered into soft material, pressed with high-tech phenol and amino plates and processed under high pressure [143]. Designer Buro Belén developed a biodegradable wooden substrate from mulberry tree bark [144]. The bark was peeled as skin and soaked in solutions for softening up. The softened material was beaten to spread the fibrous stuff in the form of sheets [117]. Aesthetically, it was matter and soft and produced a warm feeling besides being scratch resistant and flexible. It was used in interior decorative textile applications [144].

5.4.4

Advantage of New Material Properties

The material experience as stated by Karana defines it as “the grasp of material properties the designer could interpret while they used them in product designs”

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[145]. Later, the material interpretations in the form of sensitivity to the five senses, their meanings and emotions bonded to them were consolidated [146]. Such consolidation of information pertaining to these novel materials provides a platform to compare them vis-a-vis with the traditional leather properties. And it also furthered the classification of new materials. Among all of them, especially the DIY materials produced by way of individual efforts or small group collective efforts with designer intervention are unique on their own. The unique properties in terms of aesthetics or engineering attributes are self-honed by the designer which also provides the royalty privileges until and unless it is mass customized. In due course of time, there might be modified versions and further developed versions of them [147]. These materials are also becoming popular for other reasons such as sustainability attributes of the material, novel unique material expressions, one of kind appeal, their exclusivity in the market due to their limited availability and in overall avant-garde categorization of products made out of it [147, 148]. For exploring the perception of the aesthetic properties and their conceptual attributes, [149] classifies the materials on the basis of the source from which they are developed. The material source categories are identified as vegetable sources, animal sources, manmade sources, etc. Materials developed out of vegetable sources naturally refer to the intrinsic variations in texture otherwise known as imperfections. These imperfections are sensitized by touch arising out of uneven surface roughness or smoothness that is attributed to their non-homogenous nature. However, the consumer’s strong predisposition about vegetable material source is their sustainable properties. The combination of natural visual appearance and sustainability properties has started to influence the user’s affective attitude according to Mangier and Schoormans [150]. In fact, the above-discussed surface unevenness has become an active stimulus to user’s cognition for it elicits various types of emotions [151]. The conception of natural materials as a healthy environmental choice holds the beliefs in ransom intuitively [79]. The most positive emotion types reported about these vegetable materials are [151] gratification followed by animation and enjoyment, while negative emotion types recorded are discontent, uncertainty and aversion. According to Wabi Sabi concept [152], imperfection is often embraced as it communicates the intrinsic unevenness of the natural materials. Natural materials lend uniqueness about it by drawing from the phases of their development and existential nature on mother earth [153]. Events and track record of its development phases have always held important in Western culture owing to its cultural and anthropological associations with the local place and its people. It is this that develops into semiotics, an indispensable attribute of every design product, thus paving the way for the development of positive emotional bond with both the material and the product [149]. The surface characteristics of these vegetable source materials and biopolymers attribute their grain texture to their morphological make-up. The intrinsic natural random variations and non-homogenous character yield uneven patterns on the surface. These surface patterns and grain make-up remain decipherable and obvious. Irrespective of the inherent grain rendering brought about by their morphological make-up, obvious differences arise as a result of variation in size and difference in

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clustering density of the grains on the surface [154]. These attributes indicate the hallmark characteristic of natural materials; in other words, they represent the pedigree traits of natural materials. Rather, it paves the way for expressing the naturalness [154]. It is the visual modality that dominates the experience in the beginning of the user–product relationship [155]. Among all the design elements, pattern and texture score the foremost on the sensorial experience scale. These material traits regarding naturalness have the potential to form long enduring relationships [147], which might end up in sustainable design obtained through emotional endurance [156]. Research about “natural” materials [153] predicted that the natural colours and patterns which show commonalities with basic aesthetic features of nature are considered to be more durable and long-lasting. Further, these surfaces are capable of being treated with different coating substances that change the tactile characteristics of the surface as well as its visual textural outlook. Beeswax, carnauba wax, latex, shellac, pine rosin and ghee are the different types of coating substances deployed for finishing both vegetable source materials. Overall, the interpretive features such as natural and handcrafted outlook attributed to its inherent visual pattern and texture along with the perceptive characteristics of the sensorial experience related to its tactile properties define the experience for these vegetable source materials which is capable of taking on the animal source materials. Sustainable materials from the animal sources such as vegetable tanned leather and other forms of skin and exoskeleton composites as already discussed owe their tactile characteristics like softness and flexibility to the presence of lanolin in the skin. Meanwhile on the visual texture front of animal source leather and skin and exoskeleton-based materials, a plethora of colouring and texturing finishes are available to render innumerable number of visual effects. The craft techniques evolved over continuously since its usage in the ancient time to what we see today. It is this amazing property of leather to converge with very many treatments that mark their versatility. The softness, suppleness, elasticity, toughness, patina and durability together index the leather as the super-luxury material. And leather surface can have matched to any synthetic or natural surface characteristic [120]. It is important to recognize that leather substitutes can offer completely consistent surface appearance and advantages in cut-component yields. It is also important to understand that some substitute materials perform better than leather in one or selected properties. In addition, these developments in materials science will produce ever-improving products [120]. While the material morphology bound characteristics such as visual texture and pattern, tactile traits are irreplaceable considering their unique value and propositions they are capable of. So, the factors to be considered while comparing leather with its potential alternative shall be comfort, durability and recyclability [120]. Due to the difference in their mechanical properties, the techniques and technologies used for construction and assembly of fashion accessories differ from the conventional craft and industrialized techniques used for leather. In addition to the material benchmark properties discussed above, its role in the society needs to be complemented for adoption [117]. The experiential studies conducted in Italy yielded the following results. The new materials shared affective connotations such as respect, kindness of

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empathy type, worship of aspiration type and surprised of animation type [117]. All these connotations fall under pleasant emotion category.

5.5 Adopting New Technologies The average handbag takes 75 steps on a factory line, while the Traveller Duffle takes around 139 steps [157]. On the contrary, XYZBAG an Italian brand advocates digital craftsmanship: it combines traditional design methods and additive manufacturing technologies to produce unique handbags. By this, 3D technology means it has made possible to manufacture the handbag straight away at few work stations in quick time. Further, it adds a wide range of flexibility in personalizing the handbag designs at the design preview stage. So, designs can be directly shown to the customers and based on the requirement they could be produced. Thus, the dimension of post-distribution unsold bags in retail stores can be weaned away [158] as it eliminates the need for holding inventory because of remarkable lead time affected by additive manufacturing. At XYZBAG not only 3D printing, traditional Italian craftsmanship is also used in combination. By virtue of cloud-based CAD software, design options based on 3 master products (DADA, GRETEL and TRADA) are shown to the potential customers. Customers have the privilege of deciding on the design with recommendations for change in details. This paves the way for customer-driven design approach and production only on demand. The benefits of additive manufacturing or 3D printing are personalized designs in terms of specification and creative attitude. Rather, it incorporates both sustainability and co-creation, the future of fashion industry. The role of customer in design interaction and co-creation adds a new dimension to the evolving fashion industry [158]. Another Designer Lana Hopkins pioneers in the production of 3D-printed handbags [159]. The sports brand Nike launched a 3D-printed sports kit bag Rebento Duffel on the eve of FIFA World cup 2014 [159].

6 Conclusion There has been several significant research developments and design process innovations imbuing faith in sustainable goals and circular design. Well waste generation in design directly translates to failure of the design. The major problems in the design and development of leather products are the impact on environment it leaves behind along the process of raw material to product form conversion and identifying appropriate second life for leather products at its end of first life. According to Burall, Author of cradle-to-cradle design approach, the designer is entitled to know the end of the products right from the product design phase itself and develop methods on how to begin another cycle [160]. So, circularity is the future that requires the coordination of designer activism strategies. Our study of the literature and case

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studies pertaining to designer activism strategies revealed the following enterprising avenues, namely; i. production of genuine leather products from by-product hides sources using vegetable tanning methods and fine craftsmanship and ii. production of fashion accessories from biodegradable and recyclable leather alternatives. Hence, understanding and appreciating the role of designers, who do not want to be confined to only the synthetic leather alternatives and the highly coated industrial leather, are important as they influence fashion and its demand [65]. From a design-thinking perspective, all the efforts seem to be directed towards producing designs on the lines of circularity. Available literature supports the claim of genuine leather products using vegetable tanning was found to be effective in cutting down the environment and hazardous impacts. Not only does such genuine leather preserve its symbolic luxury image along the fashion domain but also it preserves the legendary craftsmanship of artisans. In a way, it fulfils the basic premise of the sustainable tenet that “Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs” [161]. Engineering circular design product from leather-based biodegradable and recyclable substrates has earned its new material experience and exclusivity in the fashion domain already. This endeavour holds promise for meeting the burgeoning demand for fashion accessories. Overall, the study helped to conclude the scope and potential growth opportunities for such designer activism strategies but could not ascertain the actual energy demands and environment impact which if carried in near future shall provide a more detailed idea for further progressive developments in circular design.

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124. https://www.leathermag.com/features/featurematerial-gains-6713680. Last accessed 8 Mar 2020 125. Modern Meadow (2019) About us. Available at: https://www.modernmeadow.com/about-us. Last accessed 5 Mar 2020 126. Modern Meadow launches Zoa, the first ever biofabricated leather material brand (2017) Modern Meadow. Available at: http://www.modernmeadow.com. Last accessed 5 Mar 2020 127. https://www.eclectictrends.com/mushroom-mycelium. Last accessed 8 Mar 2020 128. Madaria D (2018) Product design history, December 1 2018, I search paper: mushroom leather 129. https://www.premierevision.com/en/news/smart-creation/frumat-apples-skins. Last accessed 8 Mar 2020 130. https://www.plantbasednews.org/opinion/10-new-innovative-vegan-alternatives-to-leather. Last accessed 8 Mar 2020 131. https://www.fastcompany.com/3059190/this-gorgeous-sustainable-leather-is-made-from-pin eapple-waste. Last accessed 8 Mar 2020 132. https://danandmez.com/blog/pinatex. Last accessed 9 Mar 2020 133. Ananas Anam, Ltd. Pinatex branding guidelines. Last accessed 5 Mar 2020 134. AFIRM Group I reduce the use of harmful substances (2019) AFIRM Group. Available at: https://www.afirm-group.com. Last accessed 6 Mar 2020 135. https://www.mymodernmet.com. Last accessed 6 Mar 2020 136. Vegetal leather. Available at: http://environment.yale.edu/publication-series/documents/dow nloads/0-9/98ginu.pdf. Last accessed 10 Mar 2020 137. Vegetal leather. Available at: http://www.lanecrawford.com/product/givenchy/-show-velourvegetal-leather-belt/_/LYK134/product.lc. Last accessed 11 Mar 2020 138. Bolt Threads (2019) Available at: https://boltthreads.com. Last accessed 10 Mar 2020 139. Tamara Orjola makes furniture and textiles using pine needles (2016) Available at: https:// www.dezeen.com. Last accessed 25 Mar 2020 140. https://www.Tjeerdveenhoven.com. Last accessed 26 Mar 2020 141. https://www.jpscorkgroup.com. Last accessed 28 Mar 2020 142. Pineskins (2018) Material district, Rotterdam, Netherlands. Available at: https://www.materi aldistrict.com. Last accessed 29 Mar 2020 143. https://www.dekodur.com. Last accessed 28 Mar 2020 144. https://www.signenorgaard.com. Last accessed 28 Mar 2020 145. Karana E (2009) Meanings of materials 146. Karana E, Barati B, Rognoli V, Der Laan V, Zeeuw A (2015) Material driven design (MDD): a method to design for material experiences 147. Rognoli V et al (2015) DIY materials. Mater Des 86:692–702 148. Ayala-Garcia C, Rognoli V (2017) The new aesthetic of DIY-materials. Des J 20(sup1):S375– S389 149. Schifferstein R, Wastiels L (2014) Sensing materials: exploring the building blocks for experiential design. In: Karana E et al (eds) Materials experience: fundamentals of materials and design. Elsevier, Oxford, pp 15–24 150. Bahrudin FI, Aurisicchio M (2018) The appraisals of sustainable materials 151. Desmet PM, Hekkert P (2007) Framework of product experience. Int J Des 1(1):57–66 152. Salvia G et al (2010) The value of imperfection in sustainable design. In: LeNS conference, Bengaluru 153. Karana E (2012) Characterization of ‘natural’ and ‘high-quality’ materials to improve perception of bio-plastics. J Clean Prod 37:316 154. Rognoli V, Karana E (2014) Toward a new materials aesthetic based on imperfection and graceful aging. In: Materials experience. Butterworth-Heinemann, pp 145–154 155. Fenko A, Schifferstein HNJ, Hekkert P (2010) Shifts in sensory dominance between various stages of user product interaction. J Appl Ergon 41(1):34–40. https://doi.org/10.1016/j.ape rgo.2009.03.007 156. Mugge R et al (2009) Emotional bonding with personalized products. J Eng Des 20(5):467– 476

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157. https://www.willleathergoods.com/blogs/news/the-traveler-duffle-deconstructed. Last accessed 11 Mar 2020 158. https://www.3dnatives.com/en/xyzbag-3d-printed-handbags-020820194. Last accessed 11 Mar 2020 159. https://www.3dprint.com/186347/3d-printed-handbags. Last accessed 12 Mar 2020 160. Burall P (1991) Green design. Design Council, London 161. Jarvie EM (1987) Brundtland report, World Commission on environment and development. Available at: https://www.brittanica.com. Last accessed 8 Mar 2020

Bacterial Cellulose—A Sustainable Alternative Material for Footwear and Leather Products R. Rathinamoorthy and T. Kiruba

Abstract Issues related to sustainability are an inevitable factor which always associated with leather products as the raw material is associated with animal slaughtering. At the same time, research agencies predicted that the footwear industry is expected to grow 371.8 billion USD in 2020 with a CAGR of 5.5%. Out of different raw materials used in the industry, leather products are occupying a significant market share as premium goods. The major pollution by the footwear and other leather products not only comes from the disposal but also from the manufacturing stages like machine usage, energy confirmations, chemicals, etc. It is estimated that approximately 50.2 m2 of land and 25,000 L of water required to develop leather boots. On average, the production of single boot emits 30 lb of carbon-di-oxide to the environment. The existing leather alternative materials like polyurethane, synthetic textiles, and rubber will take roughly 50 years to decompose totally. Material selection is one of the important solutions for sustainability-related issues and to reduce the negative environmental impacts. Bacterial cellulose is one such material that attracted the footwear industry due to its special properties like unique structure, biodegradability, mechanical strength, and high crystallinity. The chapter discusses various research works performed on leather alternative materials and specifically details the potential nature of bacterial cellulose. The production method, factors influencing the production, material properties, and application scopes will be analyzed with specific concern on the leather and footwear industry. The chapter also details the advantages of bacterial cellulose over other alternative material in terms of wearer comfort, durability, disposability, biodegradability, and cost factors. Keywords Footwear industry · Sustainability issues · Bacterial cellulose · Production · Properties · Leather alternative

R. Rathinamoorthy (B) · T. Kiruba Department of Fashion Technology, PSG College of Technology, Coimbatore 641004, India e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. S. Muthu (ed.), Leather and Footwear Sustainability, Textile Science and Clothing Technology, https://doi.org/10.1007/978-981-15-6296-9_5

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1 Introduction Animal leather is used in apparel, accessories, furniture, and upholsteries due to its unique characteristics like higher esthetic, rich look along with its flexibility and durability. Out of the total leather produced, approximately 25% of leather produced is used in the footwear industry. The remaining percentage majorly occupied by clothing, furniture and upholstery application. The main objective of the leather industry is to process the animal skin or animal hides into useful material for several applications. In this process, the skin or hide is subjected to several chemical and physical treatments subsequently and this process is called tanning. Due to the excessive usage of water and chemicals, leather industries tend to pollute the environment in terms of bad smell, organic wastes, and leather processes effluents. The level of pollution caused by each industry is different from each other based on the types of skins used in the process and their required process sequence for the hides and skins processed. Hence, the waste produced from each industry also defers significantly based on the process adopted. In general, this process causes air, water pollution, solid organic waste disposal, and a higher amount of bad odor and toxic gas generation. The leather processing industries are identified as one of the highly polluting industries due to the use of a lot of toxic chemicals used in the tanning process and disposal of wastes. The effluent from the leather tanneries contains a higher quantity of toxic chemicals like chromium slats and metal ions which ultimately increases the biological oxygen demand and makes the water the most polluted one. One of the other issues with the leather processing and tanning industry is the generation of unpleasant odor to the environment due to the decomposition of protein waste along with sulfides and ammonia used in the tanning process [1]. Reports indicated that approximately 800 kg of solid wastes are developed during a ton of rawhide processing along with the emission of harmful chemical substances like chromium salts, sulfuric acid, sulfides, ammonium salts, and vegetable tanning materials. Further, most of the industries discharge the unprocessed tanning effluent into the soil which affects the soil productivity at a major level along with significant environmental pollution. Figure 1 represents the activities involved in the conversion of rawhide into leather [2]. The first section of the leather manufacturing industry is to handle the animal skins to prepare the rawhide. This section is generally known as beam house. In this process, the animal skin is soaked in water and processed for fleshing and unhairing of skin. Finally, the skin is treated with lime and other chemicals to dissolve hair. The second step in the leather manufacturing is tanning process in which the animal skin is processed for the removal of proteinaceous matter and stabilized. For this purpose, tanning chemicals like chromium salts, zirconium, etc. were used. As the process is performed in the acidic medium, the wastewater discharged from the process is highly acidic. The last step of the leather production is finishing activity where the tanned skin is re-tanned and then finished as per the requirement. Further at this stage, the tanned skin is treated with dye for coloring or bleached and lubricants applied based on the final endues requirements. During this skin or hide to leather

Bacterial Cellulose—A Sustainable Alternative Material …

Presoaking

Soaking

Liming

Washing after fleshing

Deliming & bating

Trimming &

93

Washing

Washing

Preparatory

Pickling

Washing

Tanning

Neutralization

Dyeing

Tanning

shaving

Retanning

Crusting Fat liquoring

Fig. 1 Process flow of rawhide to leather conversion

conversion process, the different forms of pollutions/wastes generated as listed in Fig. 2. Fig. 2 Types of waste generated from the leather processing industries

Solid waste

Waste Water

Wastes generated from Leather industry

Toxic

chemcials

Volatile Organic

Compounds

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In leather production activity, the degraded hide, hair from the first stage of the skin process and trimmings are the major solid wastes developed. Though the leather is biodegradable in nature, the treatment process involved during the tanning process converts this waste leather as the non-biodegradable one at the disposal. The tanning process is one of the most toxic processes in the leather processing sequence and it majorly contributes the wastewater pollution. Due to the treatment nature, the effluent released from the tanning process is highly acidic and so the pH of the effluence causes higher chemical oxygen demand (COD). Also, the added chemicals like sulfates and chloride during the second phase of the leather making develop higher total dissolved solids (TDS) in the wastewater [3]. Researchers also identified that the usage of sodium sulfide in the tanning process not only causes pollution in terms of TDS but also reduces the effluent treatment efficacy during the post-tanning process. Sometimes, the poor processing of leather with chrome results in higher environmental pollution by leaching in the subsequent processing stages. The posttanning activity causes higher metal pollution in the wastewater. These chemical sediments in the water bodies adversely affect the ecological balance in the aquatic life [4]. In the case of volatile organic compounds (VOC), the leather industry is well known for its emissions like ammonia, hydrogen sulfide, volatile hydrocarbons, amines, and aldehydes. The major source of pollution is the manufacturing process and tannery plant effluents. During the leather manufacturing first stage, beaming room, the ammonia is majorly emitted from the process like de-liming, unhairing, or drying processes. Further, the liming and subsequent washing processes are responsible for the release of sulfides. In the leather buffing process, the chromium is emitted as a result of the handling of chromic sulfate powder or directly from the tanning process, in which the chromate is reduced as chromium on treatment. Finally, the effluent obtained from the tanning process is highly acidic as mentioned earlier. Out of the treatment or storage of effluent, a higher amount of hydrogen sulfide is released as a major pollutant [5]. The other important pollution source in the leather conversion process is toxic chemicals used in the manufacturing stages. The previous researcher performed a detailed analysis of the various chemicals used in the leather industries and their toxic nature as listed in Table 1 [4]. Though the regulatory bodies have implemented serious regulations on using harmful chemicals in the leather industry, the usage of chemicals is still in practice. The most commonly used plasticizers in the leather industry are phthalates. This chemical has a major influence on the reproductive systems of animals and human and so the usage of the chemical is restricted to 0.5% on the final product. During the leather final finishing process, two different chemicals used, namely nonylphenol and biocides. Whereas the nonylphenol is more of non-biodegradable and so the usage on the final product is restricted to 0.1% [6], the biocides are mainly the water-based chemical used to restrict the microbial growth on the surface of the leather. The usage of these chemicals also restricted due to its irritant nature. Another important chemical used in the coalescence, plasticizing, leveling, and wetting and as a swelling agent is N-Methyl pyrrolidone. This finish provides a highperformance finish to the leather; at the same time, it is identified as a reproductive

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95

Table 1 Toxicity of chemicals used in the leather industry [4] S. no.

Name

Uses

Target organs

1.

Benzyl butyl phthalate

Used in process for the production of a microporous artificial leather coating/water vapor-permeable sheet materials

Eyes, lungs, liver, reproductive system

2.

Bis(2-ethylhexyl) phthalate (DEHP)

Used as plasticizers in the Liver and testes processing of shoe soles, and artificial leather manufacturing

3.

Dibutyl phthalate (DBP)

Used as a phthalate plasticizer in the artificial leather industry

Eyes, lungs, gastrointestinal tract, testes

4.

Anthracene

Used as a tanning agent (for leather)

Kidney, liver, fat, and carcinogen

5.

Short-chain chlorinated paraffin’s (PBT)

Additive for the leather Liver, kidney, thyroid, and treatment (renders carcinogen smoothness to leather), leather clothing and belts and as a leather oiling agent

6.

Sodium dichromate

The principal raw material Blood, kidneys, heart, used in the production of lungs, eyes, and chrome-tanning materials for carcinogen the leather industry like chrome-tanning salts

7.

Cobalt dichloride

Used in leather dyeing and finishing as well found in tanned leather

Lungs, liver, kidney, heart, skin

8.

Nonylphenol

Used in finishing

Blood, lungs, eyes, skin, CNS, kidneys and low biodegradability

9.

Methyl isothiazolinone

Biocide, microbiological protection

Skin, eyes, and carcinogen

10.

N-methyl pyrrolidone

Coalescence, plasticizers, wetting agent

Eyes, kidney, lymphatic system, liver, lung, testes

11.

Formaldehyde Heavy metals arsenic

Leather finishing

Eyes, lungs, and carcinogen Liver, kidneys, skin, lungs, lymphatic system and carcinogen

12.

Chromium

Used for dyeing

Kidney, CNS, hematopoietic system

13.

Organotin compounds (dibutyl tin)

As a catalyst

The gastrointestinal tract, liver, and carcinogen (continued)

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R. Rathinamoorthy and T. Kiruba

Table 1 (continued) S. no.

Name

Uses

Target organs

14.

Azo dyes (orange II)

Used for dyeing

Blood, liver, testes, and carcinogen

toxin by the California Office of Environmental Health Hazard Assessment [7]. Similarly, formaldehyde is used as a cross-linking agent in the top coating process of the leather; however, due to its carcinogenic nature, the usage is banned by regulatory bodies. The other most important chemical pollutions from the leather industry are the inorganic pigments, synthetic, and azo-based dyestuffs used in the coloration process. The toxic heavy metals like lead chromate and cadmium are commonly used in the leather industry due to its efficient color and superior fastness properties [8]. The results of previous research works reported that 1 ton of the wet salted hide can yield 200 kg of useful leather and this amount is approximately 20% of the total raw material processed. In this process, more than 600 kg of solid waste created this is approximately 60% of the total raw material [9]. These wastes are disposed into the environment without processing further. In this process, nearly 50 m3 of water is generated per ton on rawhide. Research data from FAO mentioned that in a year, approximately 11 million tons of rawhide is processed, and by results, 8.5 million tons of solid waste produced [10]. Higg index, a popular indexing method of environmental impact caused in the apparel production process, measured the leather industry pollution to 159 points. It is very high when compared to the high index of 44 for polyester, and for cotton, it is 98. The highest value of this index represents the contribution of the particular manufacturing industry toward global warming and water pollution [11]. Out of all the process stages mentioned in Fig. 1, the process stage two, known as the tanning process, causes 90% of the pollution in leather manufacturing. It produces higher carcinogenic chemical discharge like lead, chromium, etc. [12]. Out of all these issues in leather production, the material is still one of the best choices for luxury products due to its elegant feel, touch, and esthetical look. The application not only limited to the clothing, footwear industry, and residential furniture but also in the marine, aviation, and automotive industry in recent times to create a luxury [13]. Other than the environmental impact caused by the various processing activities of the leather industry the usage of leather also linked with animal cruelty. The People for the Ethical Treatment of Animals (PETA) indicate that the increased sales of leather goods may increase the sufferings of these animals during the process of transportation. Further to add, the association claims that though the leather produced from the domestic animals, sometimes the exotic animals are also haunted for its skin [14].

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2 Synthetic and Bioleather Alternatives As an alternative to animal leather, there are several materials used in commercial products. These alternative materials are highly abundant and cost-effective than animal leather. In general, polyvinyl chloride (PVC) and polyurethane are the most commonly used synthetic materials due to its higher temperature stability, chemical compatibility and availability [15]. Another most explored synthetic material as a substitute for animal leather is the thermoplastic polymer, polypropylene. One of the main advantages of the polymer is resistant to the environment and nonbiodegradable. At the same time, the effect of sunlight and UV radiation has a significant influence on the properties of the polypropylene. Even though the synthetic alternative materials are free from animal cruelty, it poses serious environmental pollution during the disposal. In order to reduce the environmental impact, researchers’ surface grafted the acrylate-functionalized soybean oil onto the gat leather with the help of UV radiation. In their study, they analyzed the grafting efficiency and their thermal stability on the goat leather. The findings revealed that soybean oil grafting is effective in leather finishing and an alternative to the existing toxic chemicals [16]. Nam and Lee developed a multilayered cellulosic structure using nonwoven cellulosic fiber mat, denim fabric, and hemp fabric and evaluated its performance against the performance of two-layered calf and pigskins leather, which is commonly used in the footwear industry. Their results were promising that the developed composite material had very good thermal equilibrium inside the footwear and also possessed superior strength and comfort properties [17]. Similarly, a patent published in the earlier decade illustrates the possibilities of producing eco-friendly leather by using polymerizing cellulosic fiber along with epoxidized and acrylated triglycerides and vinyl monomers. The developed composite is cast using molds as per the requirements [18]. Cao et al. developed en eco-friendly leather from chicken feather composite material as a substitute for animal leather. They developed footwear with feather fiber-reinforced composite for footwear applications. But at the same time, the researcher did not analyze the properties of the developed product in terms of thermal comfort and tensile strength, which is essential for a footwear application [19]. In recent times, there are several research works performed around the world in order to find an eco-friendly substitute for leather. Pinatex is one of the commercialized leather alternative materials manufactured from waste pineapple leaves. The extracted fibers are degummed, washed, and allowed to dry. The dried fibers were converted into a nonwoven mat and then passed to a special finishing process which makes the mat to look like leather. As the material is totally natural and no synthetic chemicals used in manufacturing, the alternative leather is claimed by the manufacture as eco-friendly material [20]. Mycelium textile is another leather alternative material researched by Stella McCartney. This type of mushrooms creates a very small microthread network during the cultivation. The researcher grows mycelium mushroom in the agricultural waste by controlling or engineering the environmental conditions so that it forms a structurally connected mat by itself. The

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materials dyed, processed, and used for the final product development. The process of converting the mushroom to a leather material is a green process and does not have any environmental impact like synthetic alternatives materials [21]. Similarly, the leading French footwear brand has launched a sustainable leather material as an alternative to animal leather from the corn. They developed a material that looks like leather made of canvas material coated with corn husk, which is a food waste mixed with polyurethane. The brand claims that the material is 63% biodegradable [22]. Zoa is a brand name that developed biofabricated leather alternative material out of the collagen obtained from yeast. The manufacturer claims that the material is very sustainable and causes no impact on the environment. Further to add, the material can be molded into any shapes, color, and texture as required. The brand released its first prototype in 2017 and yet to launch its commercial vegan leather in the forthcoming year [23].

3 Bacterial Cellulose—A Potential Substitute Bacterial cellulose is a kind of pure cellulose than the plan origin cellulose. It is one of the sustainable biomaterials which recently attracted may researchers from various disciplines like medicine, food, chemistry, textile, fashion, environmental and other engineering areas. The main advantage of the bacterial cellulose over the plant cellulose is its pure structural form which is free from the impurities like hemicelluloses, pectin, and lignin as present in the plant cellulose. The second and very unique nature of bacterial cellulose material’s self-assembled formation produces a nanostructured three-dimensional fiber network during the formation. The micromorphology generates more interfebrile space in the fiber matrix and the nanofiber shape produces a higher surface area compared to normal plant cellulose [24]. There are several bacterial species are identified as capable of synthesizing cellulose called Sarcina, Agrobacterium, Rhizobium, and Acetobacter also called Gluconacetobacter. Among the genera of identified species Acetobacter xylinus, an acetic acid-based bacterium is noted as capable of producing cellulose in the larger quantity for commercial application. Even though the bacterial cellulose is identified a century before, the research on the bacterial cellulose gained momentum in the recent time [24]. It is identified that cellulose production in the bacterial strains is an action of the protective mechanism of the strains from the environment, fungus, and various yeasts. As the bacteria segregate the cellulose as a byproduct of its growth, the cellulose fibrils are nearly 100 times smaller than the available pant cellulose. The properties of the developed cellulose depend upon the culture medium and the carbon source used for the production of the cellulose [25]. The cellulose production using bacteria is mainly depending upon the actual nitrogen and carbon contents in the source medium used for the production [26]. The first and foremost important nutrient for bacterial cellulose production is a carbon source, which helps in cell metabolism and cell growth of the bacteria type. Sugars and derivatives of the sugars are the main sources used for the production. Commonly

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sucrose, glucose, and fructose are used for the production of bacterial cellulose. Similar to the carbon source, nitrogen sources help in the cell growth of the bacteria. The most commonly used nitrogen sources in the bacterial cellulose production are ammonium sulfate, peptone, glycin, yeast extract, and casein hydrolysate. The cellulose synthesis is a function of oxygen supply and pressure. The researchers noted that the cellulose production was a very negligible amount under the nitrogen, and at the same time, a relatively higher production noted when the set up is exposed to the atmospheric air. Hence, the cellulose formation at the top of the beaker will be higher than the lower part of the layer which is in contact with the liquid [26]. During the cellulose production, the culture media can be used in two methods for the cellulose production, 1. Static culture—The culture media, after inoculation, kept it undisturbed for a specific period of time and so the layer of cellulose structure forms on the top of the media. 2. Agitated culture—The media kept in a shaker and continuously agitated for the whole period of time. Hence, the cellulose formed in the shape of irregular pellicles on the surface. Out of the abovementioned two methods, the most widely adopted method for quicker production of bacterial cellulose is the agitated method. However, the irregular growth and various fiber diameters of nanofibers formed in this method in this process. For many proposed commercial applications like wound dressing, textile and fashion material, masks for cosmetic application, etc., the cellulose must be in the form of the continuous sheet. Hence, based on the application requirements, static culture method capable of producing the industry expected outputs. There are many research works performed in the static culture method and the cellulosic films developed in the nonwoven sheet form [27–29]. The appearance of the bacterial cellulose at different stages of production is provided in Fig. 3. Figure 3a shows the tea extract with bacterial cellulose inoculated at day one with a kombucha SCOBY. Figure 3b shows the fermentation setup and Fig. 3c the fifth day after the fermentation process, the formation of immature cellulose film, on the surface of the static culture medium. Figure 3d indicates the fermented cellulose layer after 14–17 days of the fermentation process. The fully grown cellulose sheet is of highly thick sheet and consists of a lot of bacterial and yeast content along with a very high quantity of water content.

4 Carbon Sources for Bacterial Cellulose As the industrial-scale mass production required simple and cost-effective sources, several researchers tried with different alternative sources for the bacterial cellulose production either along with the standard HS medium [30] or without the HS medium [31]. However, the recent trend in the research is more focused on the utilization of various wastes material as a carbon source material. Table 2 represents various

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Fig. 3 Various stages of bacterial cellulose production

research works performed on bacterial cellulose production with different wastes as carbon or nutrient source. Similarly, the few researchers also developed bioreactors to increase the cellulose yield from the existing medium and bacterial strains. Hornung et al. developed a bioreactor to feed the glucose and oxygen directly into the cells to develop the bacterial cellulose yield in the beaker [60]. Another research work developed a rotating bioreactor to reduce the production time of the bacterial cellulose [61]. An aerosol spray bioreactor was built to spray the glucose and oxygen directly into the living bacteria and air interface for economic production of the bacterial cellulose [60]. In other methods, a plastic composite supports were included in the fermentation medium, in order to increase the cellulose fermentation. The incorporation of the plastic composite support in the culture medium had a significant increase in production. However, they reported that the material properties of the developed bacterial cellulose are different while producing in the presence of plastic composite support [62]. Shah et al. developed surface-modified reactors by using agar coating at the bottom of the reactor. They had dissolved the agar and basal medium in the distilled water and coated in the bioreactor along with a control medium. In results, maximum production was noted in the developed bioreactor when compared to the control reactor [63]. A similar research performed with silicone rubber membrane

Bacteria

Gluconacetobacter xylinum ATCC 23768

Acetobacter xylinus 23769

Acetobacter xylinum BPR2001

Acetobacter xylinum ATCC 10245

Acetobacter xylinum NRRL B-42

Acetobacter xylinum NRRL B-42

Gluconacetobacter xylinum ATCC 23768

Gluconacetobacter xylinus NRRL B-42

Acetobacter xylinus ATCC 23770

Acetobacter xylinum 0416 MARDI

Gluconacetobacter xylinus BCRC 12334

Acetobacter xylinum

S. no.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

Sugarcane juice

Orange peel fluid and orange peel hydrolysate

Extracted dates syrup

Enzymatic hydrolysate of wheat straw

Grape bagasse

Blackstrap and brewery molasses

Corn steep liquor

Grape pomace

Sugar cane molasses

Molasses

Hot water extract

Scum of sugarcane jaggery

Source

Table 2 Different carbon sources used for bacterial cellulose production Additional nutrients

3.05 g/L

6.7 g/L

6.7 g/L

223% as compared to 100% in HS medium

5.30 g/L

0.15 g/L

2.51 g/L

Productivity

5.8 g/L

8.3 g/L

Nil

11 g/L

Acetate buffer, peptone, and yeast 3.40 g/L extract

Components used in HS medium

Components used in HS medium

Diammonium phosphate and corn 8.0 g/L steep liquor

Nil

Nil

Nil

Amino acids, vitamins, minerals, and carbohydrates

Corn steep liquor

Nil

Nil

(continued)

[41]

[40]

[39]

[38]

[37]

[36]

[34]

[34]

[35]

[34]

[33]

[32]

References

Bacterial Cellulose—A Sustainable Alternative Material … 101

Bacteria

Acetobacter xylinum

Gluconacetobacter Sp

Acetobacter xylinum

Acetobacter xylinum DSMZ2004

Gluconacetobacter xylinus CH001

Gluconacetobacter xylinus BCRC 12334

Gluconacetobacter xylinus ATCCR 10788TM

Gluconacetobacter xylinus ATCC 23770

Acetobacter xylinum ATCC 10245

Gluconacetobacter xylinus ATCC 700178

Gluconacetobacter xylinus CH001

S. no.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

Table 2 (continued)

Source

Waste yeast biomass

Carob and haricot bean medium

A water-soluble fraction from pulping waste liquor

Waste fiber sludge sulfate and sulfite fiber sludges

Makgeolli sludge filtrate

Thin stillage (TS) wastewater

Discarded waste durian shell

Poor quality apple residues in combination with glycerol

Rice bark

Grape

Coconut water and sugar palm juice

6.26 g/L

2.67 g/L

8.6 g/L

–

7.47 g/L

Productivity

11 g/L

Nil

Nil

2.9 g/L

3.2 g/L

Other components are the same as High yield of HS medium

Yeast extract and tryptone

Other components are the same as 1.6 g/L of HS medium

TS and HS medium were mixed with different portions to prepare TS-HS medium

Nil

Apple glucose equivalents, glycerol, ammonium sulfate and citric acid

Glucose, yeast extract, peptone, Na2 HPO4 , citric acid

Cane sugar (5%)

2 g ammonium sulfate (NH4 )2 SO4 and 0.5 mL glacial acetic acid

Additional nutrients

(continued)

[52]

[51]

[50]

[49]

[48]

[47]

[46]

[45]

[44]

[43]

[42]

References

102 R. Rathinamoorthy and T. Kiruba

Bacteria

Gluconacetobacter xylinum BC-11

Gluconacetobacter xylinus CH001

Acetobacter xylinum KJ1

Gluconacetobacter xylinus

Gluconacetobacter xylinus DSM 46604

Acetobacter xylinum

Acetobacter xylinum

S. no.

24.

25.

26.

27.

28.

29.

30.

Table 2 (continued)

Rice bran

Rice waste water

Glycerol from biodiesel industry

Waste dyed cotton fabrics hydrolysate

Saccharogenic liquid food wastes

Lipid fermentation wastewater

Wastewater after pullulan polysaccharide fermentation

Source

Components used in HS medium

Glycerol and chitosan

Yeast extract, ammonium sulfate, potassium hydrogen orthophosphate, and magnesium sulfate

Peptone and yeast extract

Nil

Nil

Nil

Additional nutrients

–

–

2.87 g/L

12.8 g/L

0.46 g cellulose/g-reducing sugar

0.659 g/L

1.177 g/L

Productivity

[59]

[58]

[57]

[56]

[55]

[54]

[53]

References

Bacterial Cellulose—A Sustainable Alternative Material … 103

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as a submerged material in the medium in different shapes like flat, tube, balloon in the shape of a cylinder. In their result, it is mentioned that the introduction of flat membrane increased the production of ten folds [64]. Wu and Li came up with different types of bioreactors by including a stirred tank, conventional airlift, and modified airlift with a rectangular wire-mesh draft tube, for the industrial-scale large production of bacterial cellulose [65].

5 Production Process Tea is one of the commonly identified media to grow bacterial cellulose by fermentation. The fermentation is generally performed to develop a drink commonly known as “kombucha.” The drink consumed worldwide due to its higher health benefits over the controversial name as unsafe medicinal tea [66]. The beverage is simply produced from the fermentation of tea leave infusions or decoction with the help of symbiotic association of bacteria and yeasts, popularly known as SCOBY [67]. Upon the fermentation, it develops a sweet, acidic beverage for the food lovers and it also creates a new SCOBY on the top of the fermenting vessel which is of our interest. The newly formed SCOBY is an aid for the next batch of tea preparation in common. Reiss details the standard procedure for the preparation of kombucha through his research and experience [68]. The details of the process are listed in Fig. 4. The general production mechanism of the cellulose from the Acetobacter xylinum is extensively documented by various researchers [69–71]. In general, the cellulose is produced from the glucose through various intermediate products material like glucose-6-phosphate, glucose-l-phosphate, and uridine-5-diphosphate glucose. In Fig. 4, the procedure is explained to prepare a fermented tea beverage for the food lovers. However, the cellulosic layer formed during the fermentation process at the top of the vessel. The SCOBY consists of millions of bacterial strains of Acetobacter species along with various types of yeasts. The bacteria and yeasts were layered with the help of the cellulosic matrix in the form of a gel. During the fermentation process, the tea infusion used in the process acts as a resource to the bacterial culture to grow and multiply and helps in the production of cellulose. Several research works performed in developing bacterial cellulose sheets using tea extract as a medium. Various potential applications of bacterial cellulose proposed by the different researchers are provided in Fig. 5. The characteristics of the bacterial cellulose are another important aspect for their wide applications. Several researchers analyzed the different properties of the cellulose in different forms namely loose fiber from the agitated medium and cellulose matt from the static culture method. The main advantage is its superior physical and mechanical properties than the plant cellulose due to its purity. The usual degree of polymerization is 4000–10,000 anhydrous glucose units compared to the plant cellulose. The crystallinity range of the bacterial cellulose is observed 80–90% compared to plant cellulose [72]. Most of the studies represented the higher water holding capacity and tensile strength properties of the bacterial cellulose sheets developed.

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One liter of normal water along with 50 grams of sugar

Add 5 grams of tea leaves and remove after 5 min through filtration process

Cool the mixture to room temperature

Add previously formed Kombucha to reduce the pH

Cover the beaker with muslin cloth to induce fermentation Make sure enough oxygen is supplied to the liquid through the cloth

Incubation at 20 – 22OC

In a week time, the fermentation process will start. (formation of gas bubble inside the liquid and fermentation smell are the indication)

New SCOBY use to float on the top (can be used for next batch preparation)

Can be fermented for 10-14 days for full fermentation

After 10-14 days, 1.5 – 2cm thick cellulose layer will be formed on the top (Known as baby scoby) Fig. 4 Steps involved in the production of bacterial cellulose using tea infusion under static culture method

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Fig. 5 Application areas of bacterial cellulose Food product

Engineering applications

Paper industry

Bacterial cellulose Leather industry

Cosmetic product

Textile and Fashion

However, the following properties were noted in specific to the bacterial cellulose [72]. • • • • • • • • • •

Higher water holding capacity Purity High crystallinity Biodegradability Hydrophilicity Mechanical strength Porosity Nanostructure High flexibility Easy moldability.

6 Bacterial Cellulose as a Leather Alternative Bacterial cellulose produced in the form of sheet and tried for its potential application in various fields like polymer industry, cosmetic products, wound dressing materials fashion industry [73]. However, due to its leather-like tactile feel, look, and properties recently, it became an alternative material for animal leather in the footwear industry [74]. The soft and stretchable nature of the bacterial cellulose along with its look made it a successful alternative material in the leather and footwear industry. Designer

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Suzanne Lee is the person who prolonged the application of bacterial cellulose to the textile and footwear sector. She is the founder of design consultancy, “BioCouture,” which makes bio-based fabrics for fashion from living bacterial species. The main objective of their research consultancy is to develop non-hydrocarbon-based feedstock for the fashion industry and her innovation is appreciated by Time magazine in 2010 [75]. Based on her research finding, later then, there are several research works performed on the bacterial cellulose for the fashion applications [76, 77]. However, in her blog, Suzanne Lee mentioned that the bacterial cellulose is just another sustainable material to save our precious natural resource but at the same time it is not a replacement or alternative for leather or cotton-like textile material [78]. Recently, Fernandes et al. tried to utilize the bacterial cellulose in the footwear manufacturing due to its excellent properties like high crystallinity, high Young’s modulus, and high water holding capacity with moldability. In spite of good properties, the bacterial cellulose membrane lost its flexibility upon drying. Hence, the researcher attempted to increase the flexibility by treating the bacterial cellulose with different plasticizers and developed bacterial cellulose composites for footwear applications. The researchers emulsified the acrylated epoxidized soybean oil with polyethylene glycol, polydimethylsiloxane, and perfluorocarbon-based polymers. The mixture is then allowed to diffuse into the bacterial cellulose nanofiber matt by the exhaustion process. The results were promising that developed bacterial cellulose polymer composite had higher flexibility and hydrophobicity than the native bacterial cellulose. The characterization results confirmed the diffusion of polymer resin into the matrix of the cellulose. However, the resultant product had poor thermal stability only up to 200 °C, higher water contact angle value, and lower tensile strength. The researcher proposed the developed bacterial cellulose composite for the upper part of the shoes [79]. Ghalachyan developed bacterial cellulose for the application of fashion accessories like leather bags and shoes as a leather alternative. They developed bacterial cellulose from the tea, sugar, and vinegar along with the commercially available kombucha SCOBY culture. Upon fermentation on multiple containers, the researcher developed gel-like bacterial structures. They dried it and used it as a sustainable alternate or substitute material for the leather. After the development, the researcher conducted a subjective analysis with different subjects on the bacterial cellulose material like the smell, feel, texture, overall liking of the material, etc. The findings of the study reported that the participants identified various parameters like; they mentioned the material is see-through, the color is tanned and looks like leather; the texture is wrinkled and unique. However, one of the major attributes the participants reported unpleasant odor or smell on the material [80]. On the extension of the study, the researcher analyzed the overall acceptability of the bacterial cellulose material based on various attributes and the results from the participants noted as the material cannot be used for the clothing application as it is see-through and rough texture and brittle. But at the same time, the leather-like look motivated the participants to accept it as different accessories like bags, hats, and shoes [80]. Though the application of bacterial cellulose is widespread in various technical fields, the textile and leather industry applications are very limited and less explored.

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The usage of bacterial cellulose will reduce the overconsumption of non-renewable fiber sources and environmental pollution. Based on this concept, few researchers came with an idea that bacterial cellulose can be used as a leather substitute in bags and clutches. The researcher developed tea-based bacterial cellulose and its leather-like reddish tone and surface texture of the developed mat are the added advantage for apparel accessories. They developed a saddle bag with laser cutting designs [81]. Studies performed in Keio University suggest the bacterial cellulose as a sustainable alternative material for the fashion. In their research, they analyzed the possibility of using it as a 3D printed mold as a part of zero-waste garment development. They reported that this method will eliminate the textile waste at the design stage. Further, they had studied the biodegradation ability of the material [82]. Bacterial cellulose was produced from Acetobacter xylinus bacteria in HS medium under the static cultivation method. The developed bacterial cellulose was treated with NaOH and bleached to get rid of un-uniform coloration. The bleached fabric is treated with 4% glycerol to increase flexibility. The developed bacterial cellulose was used as an alternative of leather ottomans, and to compare its properties, the commercial leather ottomans were purchased and analyzed. The researcher reported that the sewing part was easy in the case of bacterial cellulose compared to the original leather and imitation leather. However, the bacterial cellulose material remained with surface wrinkles and a paper-like look. It was reported that the final whiteness of the developed bacterial cellulose is lesser than the white noted immediately after bleaching. Among the selected materials, original leather noted to be whiter and smooth in surface with a typical leather smell. The developed bacterial cellulose possessed no smell and it is the thinnest of all with higher surface texture [83]. Lee et al. reported that the Komagataeibacter can produce cellulose pellicles either alone or along with the other bacteria and yeast aerobically. It is also noted that the developed cellulose pellicles can be produced with the desired thickness, along with the leather-like flexible material. The author also suggested that this leather-like material can be used as a substitute in the leather and shoe industry but they have also mentioned that it is not optimized so far concerning the footwear industry [73] (Table 3). Yim et al. analyzed the effect of tea type as a nitrogen source and the bacterial cellulose development and its surface properties along with sugar as a carbon source. They also evaluated the effect of carbon and nitrogen source on the yield percentage and thickness of the bacterial cellulose. In characterization, they had reported that green tea as nitrogen source and sucrose as carbon source produced the highest yield and with a smooth surface. They evaluated the mechanical properties like thickness, strength and concluded that bacterial cellulose looks like leather and it has higher tensile strength than the top grain leather of similar thickness [29]. Nam and Lee developed bacterial cellulose based on Suzanne Lee’s biofabric concept. The researchers developed synthetic-free nonwoven from the biomaterials. They developed shoes using the bacterial cellulose instead of animal/synthetic leatherbased on the concept of Scarlett and Rhett, a famous character from the American novel. They also presented that the material is self-colored and so no dyeing used to replicate the leather look [85]. Researchers also developed leather material from

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Table 3 Benefits of the implementation of BC in the footwear industry [84] S. no. Issues with leather

Benefits of bacterial cellulose

1.

The manufacturing process and maintaining stock is not an environmental friendly process as it releases greenhouse gas

Bio-based production method which is more sustainable

2.

The production process uses harmful chemicals like chromium, chromium III. etc.

No chemicals used in the production process

Disposal management is very critical and mostly landfilled. Which causes higher environmental pollution

Bacterial cellulose is biodegradable and creates no pollution during the disposal

Sometimes causes allergy to the user

Skin-friendly and no allergic reactions

Possibilities of defects and rejections are high

As it is industrially manufactured, the defects can be avoided and produced as such per the requirement (size, thickness, etc.)

Cost of the animal hide is very higher

Comparatively cheaper

kombucha bacterial culture using different carbon source material other than tea. In research, the commercial sugar was replaced with culled and rotted sweet potatoes are to serve as the sugar source for cellulose production. They have performed the production with different concentrations of sweet potato. During the development, the major issue noted in the cellulose layer is uniformity and quality [86]. With specific consideration to the medical applications of footwears, a research report mentioned that it is expected that to grow 552 million diabetic patients in 2030 from 366 million in 2020 [87]. The major issue with diabetic patients is foot ulcers. Researchers reported that the functionalization of bacterial cellulose material may be a suitable alternative material for the medial footwear sector. The mechanical or chemical characterization along with the proper control of cultivation parameters will yield tailor-made bacterial cellulose for diabetic foot ulcer patients [88]. Other researchers developed bacterial cellulose-based composite material with the help of poly(fluorophenol) and laccase. During the bacterial cellulose production phase, the laccase is efficiently incorporated into the bacterial cellulose nonwoven. Further functionalization with fluorophenol resulted in hydrophobic surfaces on the bacterial cellulose along with improved wetting contact for oils. The researchers also evaluated its efficiency against washing and other mechanical properties after the functionalization and suggested the product as a suitable material for shoes and bags as an alternative material [89]. Many research works indicated that the higher water absorption capacity as an added advantage of the bacterial cellulose based on the specific application. However, when the bacterial cellulose is used in the products like shoes, leather jacket apparel, etc., the water absorption and holding capacity of the material is critical. In this

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regard, few research works were performed to reduce the moisture handling properties of the bacterial cellulose. Researchers modified the bacterial cellulose using a fabric softener and hydrophobic finishing agent immediately after the fermentation process. In this analysis, they found that the application of softener followed by hydrophobic finish provided better results without affecting the other characteristics of the bacterial cellulose than the hydrophobic finishing followed by the softener treatment method. The results were significant based on water and oil contact angle test and the researchers suggested the applications as home and interior textiles [90]. There are some research works performed on the bacterial cellulose produced from the coconut water as a substitute for leather products like shoes and bags. In the late nineties, the first bacterial cellulose from the coconut was produced and used as a leather alternative material in the shoe manufacturing process. The idea was developed by Dr. Anselmo S. Cabigan and he researched with his student Amparo Arambulo of St Paul University, QC, Philippines. They developed shoes from the bacterial cellulose developed from the coconut water famously known as nata-de-coco. They developed, dried it to the consistency of leather and developed the product and their shoes passed the DOST test for strength and durability surpassing animal and artificial leather [91]. An Indian start-up company started making leatherlike products from coconut water. This is a similar process like kombucha but the raw material is coconut water instead of tea. The startup was founded by Zuzana Gombosva, a Slovakian designer and researcher, and Susmith Suseelan, an engineer from India. They learned the process from the materials library and initiated the process as like kombucha fermentation. The coconut water is inoculated with bacterial strain and allowed to ferment for two weeks. After the defined time, the bacterial jelly is formed on the surface of the broth by the full growth of the bacteria. They named the product as “Malai.” After the production, they blend the material with various natural fibers like banana, hemp, etc. to obtain various esthetic looks and textures. In the total manufacturing sequence, there are no synthetic materials used and so the founders claim their products like shoes and bags manufactured out of the bacterial cellulose composites are totally environment-friendly and biodegradable. They claim that even though it is manufactured on a large scale, the heat and energy produced in the manufacturing process are very less [92]. Other researchers from the private patenting office had initiated the possibilities of developing bio-based leather alternative material as an eco-friendly imitative. They had developed baby shoes from the bacterial cellulose sheet developed from kombucha after the dyeing process [93]. Payne reported that they had developed cellulose form kombucha for the making of footwear. They have treated the developed cellulosic fabric with wax to improve its hydrophobic nature without affecting the tensile properties and comfortability of the material. Out of their product, they have developed footwear using the bacterial cellulose as an alternative material for leather. In their research, they outlined that the bacterial cellulose can be developed in tailormade shapes and so it can be used as zero-waste manufacturing [94]. Table 4 represents the different products developed using bacterial cellulose by various researchers as a substitute for leather products.

Kombucha culture in tea medium

2.

Materials used Kombucha culture in tea medium

Product

1.

S. no.

Table 4 Bacterial cellulose products produced from different sources as a leather alternative References

(continued)

[80, 81]

[95]

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Acetobacter xylinum in HS medium

4.

Materials used Kombucha culture in tea medium

Product

3.

S. no.

Table 4 (continued) References

(continued)

[83]

[82]

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Kombucha culture, tea medium

6.

Materials used Kombucha culture, tea medium

Product

5.

S. no.

Table 4 (continued) References

(continued)

[29]

[84]

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Acetobacter aceti bacteria in nata (coconut)as medium

8.

Materials used Kombucha culture in tea medium

Product

7.

S. no.

Table 4 (continued) References

(continued)

[91]

[85]

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Kombucha culture in tea medium

10.

Materials used Acetobacter bacteri, coconut water, and wastes as medium

Product

9.

S. no.

Table 4 (continued)

[94]

[92]

References

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7 Challenges and Future Prospective Bacterial cellulose is currently being developed at the laboratory level by various researchers and none of the research works performed in the previous decade was commercialized so far. There are so many technical and application issues noted with the bacterial cellulose in the commercialization point of view, either in the leather industry or in the apparel industry. From the previous research analysis, the following points were noted as major challenges in commercial implementation. • One of the most identified properties of the bacterial cellulose is higher water absorption capacity and higher wettability properties. These properties were advantageous for specific applications like wound dressing, etc. However, this nature of the bacterial cellulose is not suitable for many applications like clothing or leather alternative. To overcome the problem, several surface modifications process was performed by researchers [96]. • Economical viability of developing bacterial cellulose is still under discussion as the synthetic media used for the production is very costly. Many researchers identified various sustainable materials for the production of bacterial cellulose as an alternative carbon source and measured the yield percentage. • Researchers identified that bacterial cellulose films mainly suffer due to moisture loss behavior. The dried bacterial cellulose film’s structure collapses during the moisture loss and loses its texture, tensile, and some other comfort and esthetic properties. • The quality and repeatability of the cellulose production were uncontrollable during the fermentation process and no works performed on process standardization. • However, the recent urge for sustainable alternative materials for the leather and footwear sector encouraged many researchers to work by focusing on the abovementioned demerits. The solution to the identified problems will help the industry to commercialize the bacterial cellulose in large-scale production with required physical characteristics.

8 Summary Bacterial cellulose is one of the biomaterials which are totally sustainable in terms of its manufacturing process and also by its nature. Due to the exiting issues in the leather and footwear industry, it seeks a suitable and viable substitution in the near future. Though the feel and look of the bacterial cellulose are similar to the leather, the material characteristics differ technically based on the manufacturing environment and nutrient sources used for the production process. In the commercialization point, many researchers attempted to improve the productivity and characteristics of the material. The research works are still in progress to optimize the production parameter to get the standard manufacturing method. Similarly, no successful attempts made

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on the selection of alternative feedstock material such as various industrial wastes. All data were in the infant stage and no large-scale production attempted. Once these kinds of barriers have prevailed over, the cellulose material developed from the biosources will be next-generation leather as a substitute to the animal and imitation leathers exists in the market.

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The Chromium Recovery and Reuse from Tanneries: A Case Study According to the Principles of Circular Economy Evgenios Kokkinos and Anastasios I. Zouboulis

Abstract In tanning procedures, the main and most widely currently used reagent for skin/hide treatment is the trivalent chromium salt (usually the sulfate one). However, the low yield of the reactions, taking place in the respective chromium bath, commonly results in a significant proportion of this metal, passing unused into the corresponding wastes (mostly wastewater, but also to some extension in the solid waste). These wastes are considered as hazardous, and their sustainable management is recommended/enforced by international and national legislative organizations. An attractive approach to address this issue is the application of circular economy principles, where the Cr(III) content of wastewaters can be appropriately recovered and then reused again into the tanning process, as raw material. The chromium-rich tannery wastes, in which Cr(III) recovery has been examined, are mainly the tanning liquor and the resulting sludge from the physicochemical/biological treatment of wastewater stream. Regarding the tanning liquor, the treatment technique that shows the highest efficiency and also applied in the field is precipitation. This method requires the addition of an appropriate alkaline media in order to increase the solution’s pH and to precipitate Cr(OH)3 ; subsequently, this precipitate can be re-dissolved in sulfuric acid, before feeding it back to the tanning bath. On the other hand, the most effective technology for chromium recovery from the tannery sludge is the selective, mainly acidic dissolution of chromium by applying simple hydrometallurgical principles, followed by precipitation and eventually re-dissolution, before reuse. Keywords Leather production · Tanning · Waste management · Chromium recovery · Circular economy · Wastewater from tanneries · Tannery sludge

E. Kokkinos · A. I. Zouboulis (B) Department of Chemistry, Laboratory of Chemical and Environmental Technology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. S. Muthu (ed.), Leather and Footwear Sustainability, Textile Science and Clothing Technology, https://doi.org/10.1007/978-981-15-6296-9_6

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1 Introduction By the term “tanning” is meant the conversion of a raw skin or hide (by-products of slaughterhouses) into a high-strength commercial material (leather), which can be further used for the manufacturing of a wide range of consumer products. As a profession, it is considered to be among the oldest in the world and also, in many cases, leather was used historically as a mean of trading goods. Nowadays, it is recognized as an industry of high economic importance. The preservation of skin by tanning and the performance of various stages of pre/treatment will result in a final product with specific practical properties, such as stability, appearance, water resistance, temperature resistance and elasticity. In other words, tanning is the fundamental stage during the treatment of skin through the application of a complex chemical series of subsequent reactions and of several physical–mechanical processes, noting also that tanning has significantly changed as technology, especially over the last decades. It is considered also mostly as an empirical and not highly scientific batch procedure, depending on several parameters, but mainly on the quality, preservation and pre-treatment of the used raw materials. Nevertheless, tanneries have been criticized numerous times, regarding their (negative) environmental footprint/impact, although other simpler alternatives to manage skins as wastes (e.g. by landfilled disposal) can be also problematic. In fact, the tanning industry is considered as an important source of pollution worldwide and the relevant wastes (such as wastewaters, sludge, residues) are under continuous monitoring by the respective environmental control organizations, since tannery wastes consist of a complex mixture of organic and inorganic pollutants, such as oxidation agents, phenols, chromium. The tannery wastewaters can be generally treated by the application of various physicochemical and biological methods, or usually by an appropriate combination of them. However, due to the complexity of different pollutants’ content, it becomes crucial to determine as quantitatively as possible their overall environmental impact (and toxicity), and hence, the respective prevention and remediation strategies can be more effectively applied. Among them, the proper pollution control devices, the minimization and safe disposal of produced wastes, the effective use of chemicals and the prevention of accidents are between the most important aspects that have to be considered by any tannery in order to reduce and control its significant environmental impact. On the other hand, specific interventions aiming at the sustainability improvement of the overall tanning processes should be carefully evaluated as a part of the respective production, e.g., what would be their financial cost? What is their effect on the convenient production processes and how this can be predicted in advance? Proposing a methodology that is capable to reduce both environmental and financial costs is always desirable and more appealing to apply. In addition, the final product quality should not be negatively affected, but remain quite the same, or even can be further improved. Indeed, in some cases by changing certain parameters of a specific treatment stage during the production process is likely to cause negative effects, regarding product quality, in the following one.

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Generally, there are main two strategies, followed primarily by the scientific community and later by the enterprises, which can promote sustainability, namely the application of green chemistry [1] and of circular economy principles [2]. Green chemistry can be briefly described as the application of certain fundamental principles, aiming mainly in waste and pollution minimization/reduction by the appropriate modification/replacement of the used toxic chemicals, whereas the circular economy promotes the exploitation for the effective reuse/recycling of by-products (previously considered as wastes), as well as of services, applied mainly in the industrial scale. Therefore, by taking into consideration the aforementioned criteria, i.e., the green chemistry and the circular economy, it seems they can be quite easily adopted in this specific industrial field (tanning). A typical case of applying the principles of circular economy in a tannery production plant is the recovery of chromium from the respective wastewaters and sludge, aiming to effective reuse. Both liquid and solid tanning wastes usually contain high concentration levels of trivalent chromium, as this is the most widespread applied chemical reagent [Cr2 (SO4 )3 ], commonly used during the skin/hide tanning procedure. However, due to the limited efficiency of respective chemical reactions taking place, leading to the limited consumption of this reagent, a significant portion (up to 40%) may end up in the produced wastewater, which subsequently requires the application of specific management/treatment techniques. On the contrary, by recovering chromium from these wastewaters, this may be reused by the same industry, as raw/feed material, rather than applying supplementary safe treatment and disposal methods. In this chapter, a simplified description of the tanning procedure is presented, along with the respective environmental impact through the respective waste production and management. The main case study is considered to be the recovery of chromium from tanneries in appropriate form to be subsequently reused also by the same industries, following the general framework of circular economy. It is worth noting that all the methodologies proposed by the literature and described in this chapter are intended, in addition to recovery, to the reuse of chromium in tanning procedures, or by other industries (e.g., electroplating), depending on the specific chromium form (speciation). These technologies were developed based on the principles of the circular economy, and therefore, the evaluation criteria were determined accordingly. In addition, a detailed description of speciation, regarding the major pollutant of interest, i.e., the trivalent chromium, in the various stages of leather production and waste production/management operations, is provided for the better understanding of the respective processes.

2 Short Description of the Tanning Procedure The first differentiation, regarding the applicable tanning process, can be considered to be the source of raw material. Especially, the term “skin” refers to the raw material delivered from sheep and goats, while “hide” is the respective term from cows and buffalos. Although the final product has almost the same specifications and it is

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Fig. 1 Basic stages of the overall tanning process

commonly mentioned as leather, despite the different source, the applicable procedures and the respecting requirements may vary. This can be attributed to the different qualitative characteristics, such as the thickness of the surface layer (epidermis) and of the subcutaneous tissues. In the following, a detailed list of the fundamental treatment stages (Fig. 1) and steps will be shortly presented, mentioning also that these are quite likely to vary, depending on the specific raw material (i.e., hide or skin). The most important between the applied treatment stages is considered to be the tanning process, and that is the reason why the whole procedure was finally prevailing to be termed also by this general term.

2.1 Pre-treatment During the following steps of pre-treatment procedure, the main objective is to prepare appropriately the skin for the subsequent tanning process in order to achieve the best possible quality result, i.e., leather with high strength, resistance to external factors (e.g., humidity, temperature) and elasticity. • Trimming and Sorting: The raw material (feed) of the tannery is likely to include some parts of the animal, i.e., not effectively removed during the slaughterhouse process, beside the skin/hide (e.g., parts of tail, head, legs), and therefore, these should be preliminary removed. Then, the skins can be classified into different grades, according to their specific size, weight or quality. • Dehydration/Storage: The removal of moisture from the skin/hide is performed by the application of large salt quantities, in order to avoid bacterial degradation during storage. However, if only a short period of storage is required, as an alternative procedure, simple cooling may be also applied. • Soaking: Then, the removal of salt is necessary before forwarding the skin/hide to the next stages of processing after storage. This procedure is performed by washing with water, while removing also other impurities (e.g., blood, dung, proteins etc.), and aiming to regain its moisture [3]. • Liming: The purpose of this procedure is the removal of hair, flesh, fat (mainly by the use of Na2 S) and the fibrous structure open-up (mainly by the use of NaOH, Na2 CO3 , Ca(OH)2 , etc. and alkaline reagents at the pH range 12–12.5).

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• Fleshing: The removal of fatty subcutaneous tissue is accomplished commonly by proper mechanical means. • De-liming: The procedure requires the adjustment of pH value in the range 8–8.5 (commonly performed by using NH4 Cl or (NH4 )2 SO4 ), which allows the collagen fibers’ matrix to be smoothly and gradually restored to the initial state. • Pickling: The pH is adjusted to the appropriate value for the following tanning step (commonly by the use of H2 SO4 and/or HCOOH, by applying quantities proportional to thickness and for the prevention of skin swelling (using NaCl) [4].

2.2 Tanning Tanning is the second treatment stage, as aforementioned, and the most crucial step during the skin/hide treatment for leather production. In the following, the most widespread applications of tanning methods are enlisted, although it has to be clarified that more than 80% of total leather production is based on chrome tanning: 1. Chrome Tanning: The applied reagent is most commonly chromium(III) sulfate (7–10% w/w) and the application pH value ranges from 3.8 to 4. When compared with the other methods, chrome tanning requires less time and addition of chemicals, while delivering better hydrophobic and softening properties of the final product. The semi-treated leather in this case commonly referred as “wet blue.” This procedure is mainly applied for the production of leather intended for clothing and for the upper part of shoes. 2. Vegetable Tanning: In this method, the applied reagents (physical tannins) are extracted from several plants (e.g., oak, spruce bark, chestnuts, willow bark, valonea, cecidia). Although the process is free from any use of toxic metals, the resulting skin/hide has comparatively reduced heat resistance and color retention. This procedure is mainly used for the production of leather intended for belts, sole and riding equipment. The semi-treated leather referred in this case as “white wet.” 3. Synthetic Tanning: The used chemical reagents in this case belong to several major categories, such as syntans, resins and polyacrylates (e.g., formaldehyde, glutaraldehyde, phenols, acrylates). Synthetic tanning was developed as an alternative procedure, but it is mostly used in combination with other tanning processes, i.e., either with chrome tanning or with vegetable tanning. The drawbacks of this method are the relative increase of moisture and the heat sensitivity. The semi-treated leather referred in this case as “wet white” and used mainly for leather goods intended for use in the car industry [5]. 4. Combination Tanning: It is quite common two of the aforementioned treatment methods to be combined, so that the skin can obtain certain specific properties. The already applied combinations are synthetic with chrome or vegetable tanning, the vegetable with subsequent chrome tanning (semi-chrome leather) and the chrome tanning followed by vegetable tanning (chrome re-tanning).

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2.3 Post-tanning At the post-tanning (i.e., the third stage) of the overall treatment process, certain specialized procedures can take place in order to improve the characteristic quality properties of the final product (leather), such as water repellence or resistance, oleophobicity, gas permeability, flame retarding, abrasion and anti-electrostatics. A short description of them is following: • Drainage: The excess moisture is removed in the “wet blue” leather mainly by mechanical means. • Trimming: The previously produced skin/hide is thickened, shaved and leveled by using the appropriate machinery. • Re-tanning: Depending on the quality of “wet blue,” skin/hide is re-tanned to improve the chromium content of the skin (necessary quality control parameter). • Neutralization: After washing the excess (acidic) chromates from the skin/hide, this is then added to a new bath with alkaline media in order to restore the pH value to a less acidic range (e.g. 4.5–6.5). • Dyeing: The skin/hide can be colored by pigments, such as anionic, metallic, acidic or basic dyes. • Fat-liquoring: The skin/hide is lubricated with an oil coating (from animal, vegetable or synthetic origin), aiming to separate the fibers, thereby to reduce the friction between them, and to result in better softness [5]. • Finishing: The final grooming is performed, according to the specific type of final leather product by applying a series of surface processes, chemical and/or mechanical, aiming in the coverage of possible defects, the delivery of the desired shade and the required durability, while the leather becomes more attractive in appearance and touch [4].

3 Major Environmental Impacts of the Tanning Process The negative environmental impact of tanneries can be attributed to the formation of several liquid, solid and gaseous waste streams, as a result of raw skin/hide treatment by the use/consumption of chemicals, energy and water. Consequently, the nature of treatment processes and the associated use of dangerous materials/components have the potential to contaminate severely soil and water. It has to be noted, however, that the application of specific alternative techniques (“Green technologies”) to the production process and the appropriate treatment of produced wastes can lead to the significant reduction of these impacts. However, this is a quite difficult task, since the quantity and quality of production wastes can vary not only from region to region, due to bigger or smaller differences in the applied tanning process technologies, but even within the same tannery industry from time to time, e.g., by the treatment of different raw materials.

The Chromium Recovery and Reuse from Tanneries … Table 1 Range of water consumption during the tanning process [6]

Treatment step Pre-treatment (stage 1)

129 Water consumption Hide (m3 /tn)

Skin (m3 /tn)

7–25

65–150

Tanning (stage 2)

1–3

30–70

Post-tanning (stage 3)

4–9

15–45

Total

12–37

110–265

3.1 Water Consumption Water consumption can be classified in two main categories, i.e., the requirements for the tanning procedure and for the overall technical part, such as house cleaning, energy production and sanitation. The latter cases are estimated to represent about one-fifth of the total water consumption by the tannery plants. According to the production monitoring of batch operating plants, it is possible to calculate the average daily needs for water and to estimate the volume of wastewater produced per raw material type and weight for each stage/steps of treatment process. It should be noted, however, that the water requirements during the tanning procedure may vary considerably between tanneries, depending on the peculiarities/differences of used processes, the raw materials (e.g., hides or skins) and the specific final product specifications. As Table 1 shows, the water consumption is higher in the early stage of tanning process and then, it is significantly reduced [5]. In addition, the constant attempts for improvement globally, have led to reduce the water consumption in tanneries to the absolute necessary quantities. For example, by the application of low-volume bath technologies along with advanced reactors, even in processes that seemed particularly difficult to be modified (e.g. calcination, tanning etc.), and also through the better organization of product lines. Nevertheless, it is estimated that about 75% of total water volume, required daily for the various treatment stages/steps and needs, may end up in the wastewaters’ stream. According to the previously mentioned facts, perhaps the term “consumption” is not the right one to describe the water used by a tannery, though it has been prevailed, because it should be then treated as high-strength wastewater. Regarding also the cooling water of the dryers, and also that used in specific machinery, this represents a rather good-quality stream and it can be easily recycled and reused into the same plant for similar purposes.

3.2 Energy Consumption The energy consumed by a tannery plant is mainly electric and thermal, with the majority being spent on the second one (~80%). This consumption depends mainly on the applied tanning methods and the specific equipment used, e.g., chrome,

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Table 2 Estimations of energy consumption for tanneries [7]

Tanning steps

Electric and thermal energy consumption GJ/t

Skin/hide to wet blue (stage 1)